Twitter

Twitter is an online social networking service and microblogging service that enables its users to send and read text-based messages of up to 140 characters, known as "tweets".

Twitter was created in March 2006 by Jack Dorsey and by July, the social networking site was launched. The service rapidly gained worldwide popularity, with over 500 million registered users as of 2012, generating over 340 million tweets daily and handling over 1.6 billion search queries per day. Since its launch, Twitter has become one of the ten most visited websites on the Internet, and has been described as "the SMS of the Internet." Unregistered users can read tweets, while registered users can post tweets through the website interface, SMS, or a range of apps for mobile devices.

Twitter Inc. is based in San Francisco, with additional servers and offices in New York City, Boston, and San Antonio.

Creation and initial reaction
Twitter's origins lie in a "daylong brainstorming session" held by board members of the podcasting company Odeo. Dorsey, then an undergraduate student at New York University, introduced the idea of an individual using an SMS service to communicate with a small group. The original project code name for the service was twttr, an idea that Williams later ascribed to Noah Glass, inspired by Flickr and the five-character length of American SMS short codes. The developers initially considered "10958" as a short code, but later changed it to "40404" for "ease of use and memorability." Work on the project started on March 21, 2006, when Dorsey published the first Twitter message at 9:50 PM Pacific Standard Time (PST): "just setting up my twttr".

"'...we came across the word 'twitter', and it was just perfect. The definition was 'a short burst of inconsequential information,' and 'chirps from birds'. And that's exactly what the product was.' – Jack Dorsey"

The first Twitter prototype was used as an internal service for Odeo employees and the full version was introduced publicly on July 15, 2006. In October 2006, Biz Stone, Evan Williams, Dorsey, and other members of Odeo formed Obvious Corporation and acquired Odeo and all of its assets – including Odeo.com and Twitter.com – from the investors and shareholders. Williams fired Glass who was silent about his part in Twitter's startup until 2011. Twitter spun off into its own company in April 2007.

The tipping point for Twitter's popularity was the 2007 South by Southwest Interactive (SXSWi) conference. During the event, Twitter usage increased from 20,000 tweets per day to 60,000. "The Twitter people cleverly placed two 60-inch plasma screens in the conference hallways, exclusively streaming Twitter messages," remarked Newsweek's Steven Levy. "Hundreds of conference-goers kept tabs on each other via constant twitters. Panelists and speakers mentioned the service, and the bloggers in attendance touted it."

Reaction at the conference was highly positive. Blogger Scott Beale said that Twitter "absolutely rul[ed]" SXSWi. Social software researcher danah boyd said Twitter "own[ed]" the conference. Twitter staff received the festival's Web Award prize with the remark "we'd like to thank you in 140 characters or less. And we just did!"

The first unassisted off-Earth Twitter message was posted from the International Space Station by NASA astronaut T. J. Creamer on January 22, 2010. By late November 2010, an average of a dozen updates per day were posted on the astronauts' communal account, @NASA_Astronauts. NASA has also hosted over 25 "tweetups", events that provide guests with VIP access to NASA facilities and speakers with the goal of leveraging participants' social networks to further the outreach goals of NASA.

In August 2010, the company appointed Adam Bain from News Corp.'s Fox Audience Network as president of revenue.

On September 14, 2010, Twitter launched a redesigned site including a new logo.

Growth
The company experienced rapid growth. It had 400,000 tweets posted per quarter in 2007. This grew to 100 million tweets posted per quarter in 2008. In February 2010, Twitter users were sending 50 million tweets per day. By March 2010, the company recorded over 70,000 registered applications. As of June 2010, about 65 million tweets were posted each day, equaling about 750 tweets sent each second, according to Twitter. As of March 2011, that was about 140 million tweets posted daily. As noted on Compete.com, Twitter moved up to the third-highest-ranking social networking site in January 2009 from its previous rank of twenty-second. Twitter's usage spikes during prominent events. For example, a record was set during the 2010 FIFA World Cup when fans wrote 2,940 tweets per second in the thirty-second period after Japan scored against Cameroon on June 14, 2010. The record was broken again when 3,085 tweets per second were posted after the Los Angeles Lakers' victory in the 2010 NBA Finals on June 17, 2010, and then again at the close of Japan's victory over Denmark in the World Cup when users published 3,283 tweets per second. The record was set again during the 2011 FIFA Women's World Cup Final between Japan and the United States, when 7,196 tweets per second were published. When American singer Michael Jackson died on June 25, 2009, Twitter servers crashed after users were updating their status to include the words "Michael Jackson" at a rate of 100,000 tweets per hour. The current record as of January 1, 2013, was set by all citizens of the Japan Standard Time Zone as the new year began, reaching a record of 33,388 tweets per second (and hence beating the previous record of 25,088, also set by Japan after a television screening of the movie "Castle In The Sky").

Twitter acquired application developer Atebits on April 11, 2010. Atebits had developed the Apple Design Award-winning Twitter client Tweetie for the Mac and iPhone. The application, now called "Twitter" and distributed free of charge, is the official Twitter client for the iPhone, iPad and Mac.

From September through October 2010, the company began rolling out "New Twitter", an entirely revamped edition of twitter.com. Changes included the ability to see pictures and videos without leaving Twitter itself by clicking on individual tweets which contain links to images and clips from a variety of supported websites including YouTube and Flickr, and a complete overhaul of the interface, which shifted links such as '@mentions' and 'Retweets' above the Twitter stream, while 'Messages' and 'Log Out' became accessible via a black bar at the very top of twitter.com. As of November 1, 2010, the company confirmed that the "New Twitter experience" had been rolled out to all users.

On April 5, 2011, Twitter tested a new homepage and phased out the "Old Twitter." However, a glitch came about after the page was launched, so the previous "retro" homepage was still in use until the issues were resolved; the new homepage was reintroduced on April 20.

On December 8, 2011, Twitter overhauled its website once more to feature the "Fly" design, which the service says is easier for new users to follow and promotes advertising. In addition to the Home tab, the Connect and Discover tabs were introduced along with a redesigned profile and timeline of Tweets. The site's layout has been compared to that of Facebook.

On February 21, 2012, it was announced that Twitter and Yandex agreed to a partnership. Yandex, a Russian search engine, finds value within the partnership due to Twitter’s real time news feeds. Twitter’s director of business development explained that it is important to have Twitter content where Twitter users go.

On March 21, 2012, Twitter celebrated its sixth birthday while also announcing that it has 140 million users and sees 340 million tweets per day. The number of users is up 40% from their September 2011 number, which was said to have been at 100 million at the time.

In April 2012, Twitter announced that it was opening an office in Detroit, with the aim of working with automotive brands and advertising agencies. Twitter also expanded its office in Dublin.

On June 4, 2012, Twitter announced the purchase of Washington, D.C. based web design agency Nclud. Upon the purchase, Nclud's co-founder and director of brand experience, Martin Ringlein, was named Twitter's new design manager. On June 5, a modified logo was unveiled through the company blog, removing the text to showcase the slightly redesigned bird as the sole symbol of Twitter.

On October 5, 2012, Twitter acquired a video clip company called Vine that launched in January 2013. Twitter released Vine as a standalone app that allows users to create and share six-second looping video clips on January 24th, 2013. Vine videos shared on Twitter are visible directly in users' Twitter feeds. Due to an influx of inappropriate content, it is now rated 17+ in Apple's app store.

On December 18, 2012, Twitter announced it had surpassed 200 million monthly active users. Twitter hit 100 million monthly active users in September 2011.

Leadership
As chief executive officer, Dorsey saw the startup through two rounds of capital funding by the venture capitalists who backed the company.

On October 16, 2008, Williams took over the role of CEO, and Dorsey became chairman of the board.

On October 4, 2010, Williams announced that he was stepping down as CEO. Dick Costolo, formerly Twitter's chief operating officer, became CEO. According to a Twitter blog, dated October 4, 2010, Williams was to stay with the company and "be completely focused on product strategy."

According to The New York Times, "Mr. Dorsey and Mr. Costolo forged a close relationship" when Williams was away. According to PC Magazine, Williams was "no longer involved in the day-to-day goings on at the company". He is focused on developing a new startup, but he became a member of Twitter's board of directors, and promised to "help in any way I can". Stone is still with Twitter but is working with AOL as an "advisor on volunteer efforts and philanthropy".

Dorsey rejoined Twitter in March 2011, as executive chairman focusing on product development. His time is split with Square (where he is CEO), whose offices are within walking distance of Twitter's in San Francisco.

In September 2011, board members and investors Fred Wilson and Bijan Sabet resigned from Twitter's Board of Directors.

In October 2012, Twitter announced it had hired Google executive Matt Derella to become their new director of business agency development.

Logo
Twitter has become internationally identifiable by its signature bird logo. The original logo was in use from its launch in March 2006 until September 2010. A slightly modified version succeeded the first style when the website underwent its first redesign.

On February 27, 2012, a tweet from an employee that works on the company's platform and API discussed the evolution of the "Larry the Bird" logo with Twitter's creative director and it was revealed that it was named after Larry Bird of the NBA's Boston Celtics fame. This detail had previously been confirmed when the Boston Celtics' director of interactive media asked Twitter co-founder Biz Stone about it in August 2011.

On June 5, 2012, Twitter unveiled its third logo redesign, replacing Larry the Bird with an updated icon simply named as the "Twitter Bird." As of this logo revision, the word "Twitter" and the lowercase letter "t" are no longer used, with the bird becoming the sole symbol for the company's branding. According to Douglas Bowman, designer of Twitter, the new logo resembles a Mountain Bluebird.

Tweets
Tweets are publicly visible by default, but senders can restrict message delivery to just their followers. Users can tweet via the Twitter website, compatible external applications (such as for smartphones), or by Short Message Service (SMS) available in certain countries. While the service is free, accessing it through SMS may incur phone service provider fees.

Users may subscribe to other users' tweets – this is known as following and subscribers are known as followers or tweeps a portmanteau of Twitter and peeps. The users can also check the people who are un-subscribing them on Twitter better known as unfollowing via various services. In addition, users have the capability to block those who have followed them.

Twitter allows users the ability to update their profile by using their mobile phone either by text messaging or by apps released for certain smartphones and tablets.

Twitter has been compared to a web-based Internet Relay Chat (IRC) client. In a 2009 Time essay, technology author Steven Johnson described the basic mechanics of Twitter as "remarkably simple":

"As a social network, Twitter revolves around the principle of followers. When you choose to follow another Twitter user, that user's tweets appear in reverse chronological order on your main Twitter page. If you follow 20 people, you'll see a mix of tweets scrolling down the page: breakfast-cereal updates, interesting new links, music recommendations, even musings on the future of education."

Content


San Antonio-based market-research firm Pear Analytics analyzed 2,000 tweets (originating from the US and in English) over a two-week period in August 2009 from 11:00 AM to 5:00 PM (CST) and separated them into six categories:


 * Pointless babble – 40%
 * Conversational – 38%
 * Pass-along value – 9%
 * Self-promotion – 6%
 * Spam – 4%
 * News – 4%

Social networking researcher danah boyd responded to the Pear Analytics survey by arguing that what the Pear researchers labelled "pointless babble" is better characterized as "social grooming" and/or "peripheral awareness" (which she explains as persons "want[ing] to know what the people around them are thinking and doing and feeling, even when co-presence isn’t viable").

Format
Users can group posts together by topic or type by use of hashtags – words or phrases prefixed with a  sign. Similarly, the  sign followed by a username is used for mentioning or replying to other users. To repost a message from another Twitter user, and share it with one's own followers, the retweet function is symbolized by "RT" in the message.

In late 2009, the "Twitter Lists" feature was added, making it possible for users to follow (as well as mention and reply to) ad-hoc lists of authors instead of individual authors.

Through SMS, users can communicate with Twitter through five gateway numbers: short codes for the United States, Canada, India, New Zealand, and an Isle of Man-based number for international use. There is also a short code in the United Kingdom which is only accessible to those on the Vodafone, O2 and Orange networks. In India, since Twitter only supports tweets from Bharti Airtel, an alternative platform called smsTweet was set up by a user to work on all networks. A similar platform called GladlyCast exists for mobile phone users in Singapore, Malaysia and the Philippines.

The tweets were initially set to a 140-character limit for compatibility with SMS messaging, introducing the shorthand notation and slang commonly used in SMS messages. The 140-character limit has also increased the usage of URL shortening services such as bit.ly, goo.gl, and tr.im, and content-hosting services, such as Twitpic, memozu.com and NotePub to accommodate multimedia content and text longer than 140 characters. Twitter uses its own t.co domain for automatic shortening of all URLs posted on its website.

Trending topics
A word, phrase or topic that is tagged at a greater rate than other tags is said to be a trending topic. Trending topics become popular either through a concerted effort by users or because of an event that prompts people to talk about one specific topic. These topics help Twitter and their users to understand what is happening in the world.

Trending topics are sometimes the result of concerted efforts by fans of certain celebrities or cultural phenomena, particularly Lady Gaga (known as Monsters), Justin Bieber (Beliebers) and fans of the Twilight (Twihards) and Harry Potter (Potterheads) novels. Twitter have altered the trend algorithm in the past to prevent manipulation of this type.

Twitter's March 30, 2010 blog post announced that the hottest Twitter trending topics would scroll across the Twitter homepage.

There have been controversies surrounding Twitter trending topics: Twitter has censored hashtags that other users found offensive. Twitter censored the #Thatsafrican and the #thingsdarkiessay hashtags after users complained that they found the hashtags offensive.

Adding and following content
There are numerous tools for adding content, monitoring content and conversations including Twitvid (video sharing), TweetDeck, Salesforce.com, HootSuite, and Twitterfeed. As of 2009, fewer than half of tweets were posted using the web user interface with most users using third-party applications (based on analysis of 500 million tweets by Sysomos).

Verified accounts
In June 2008, Twitter launched a verification program, allowing celebrities to get their accounts verified. Originally intended to help users verify which celebrity accounts were created by the celebrities themselves (and therefore are not fake), they have since been used to verify accounts of businesses and accounts for public figures who may not actually tweet but still wish to maintain control over the account that bears their name - for example, the Dalai Lama.

Mobile
Twitter has mobile apps for iPhone, iPad, Android, Windows Phone, BlackBerry, and Nokia S40. There is also version of the website for mobile devices as well as SMS and MMS service.

Authentication
As of August 31, 2010, third-party Twitter applications are required to use OAuth, an authentication method that does not require users to enter their password into the authenticating application. Previously, the OAuth authentication method was optional, it is now compulsory and the user-name/password authentication method has been made redundant and is no longer functional. Twitter stated that the move to OAuth will mean "increased security and a better experience".

Rankings
Twitter is ranked as one of the ten-most-visited websites worldwide by Alexa's web traffic analysis. Daily user estimates vary as the company does not publish statistics on active accounts. A February 2009 Compete.com blog entry ranked Twitter as the third most used social network based on their count of 6 million unique monthly visitors and 55 million monthly visits. In March 2009, a Nielsen.com blog ranked Twitter as the fastest-growing website in the Member Communities category for February 2009. Twitter had annual growth of 1,382 percent, increasing from 475,000 unique visitors in February 2008 to 7 million in February 2009. In 2009, Twitter had a monthly user retention rate of forty percent.

Demographics
In 2009, Twitter was mainly used by older adults who might not have used other social sites before Twitter, said Jeremiah Owyang, an industry analyst studying social media. "Adults are just catching up to what teens have been doing for years," he said. According to comScore only eleven percent of Twitter's users are aged twelve to seventeen. comScore attributed this to Twitter's "early adopter period" when the social network first gained popularity in business settings and news outlets attracting primarily older users. However, comScore also stated in 2009 that Twitter had begun to "filter more into the mainstream", and "along with it came a culture of celebrity as Shaq, Britney Spears and Ashton Kutcher joined the ranks of the Twitterati."

According to a study by Sysomos in June 2009, women make up a slightly larger Twitter demographic than men — fifty-three percent over forty-seven percent. It also stated that five percent of users accounted for seventy-five percent of all activity, and that New York City has more Twitter users than other cities.

According to Quancast, twenty-seven million people in the US used Twitter as of September 3, 2009. Sixty-three percent of Twitter users are under thirty-five years old; sixty percent of Twitter users are Caucasian, but a higher than average (compared to other Internet properties) are African American/black (sixteen percent) and Hispanic (eleven percent); fifty-eight percent of Twitter users have a total household income of at least US$60,000. The prevalence of African American Twitter usage and in many popular hashtags has been the subject of research studies.

On September 7, 2011, Twitter announced that it has 100 million active users logging in at least once a month and 50 million active users every day.

In an article published on January 6, 2012, Twitter was confirmed to be the biggest social media network in Japan, with Facebook following closely in second. comScore confirmed this, stating that Japan is the only country in the world where Twitter leads Facebook.

Funding


Twitter raised over US$57 million from venture capitalist growth funding, although exact numbers are not publicly disclosed. Twitter's first A round of funding was for an undisclosed amount that is rumored to have been between US$1 million and US$5 million. Its second B round of funding in 2008 was for US$22 million and its third C round of funding in 2009 was for US$35 million from Institutional Venture Partners and Benchmark Capital along with an undisclosed amount from other investors including Union Square Ventures, Spark Capital and Insight Venture Partners. Twitter is backed by Union Square Ventures, Digital Garage, Spark Capital, and Bezos Expeditions.

In May 2008, The Industry Standard remarked that Twitter's long-term viability is limited by a lack of revenue. Twitter board member Todd Chaffee forecast that the company could profit from e-commerce, noting that users may want to buy items directly from Twitter since it already provides product recommendations and promotions.

The company raised US$200 million in new venture capital in December 2010, at a valuation of approximately US$3.7 billion. In March 2011, 35,000 Twitter shares sold for US$34.50 each on Sharespost, an implied valuation of US$7.8 billion. In August, 2010 Twitter announced a "significant" investment lead by Digital Sky Technologies that, at US$800 million, was reported to be the largest venture round in history.

Twitter has been identified as a possible candidate for an initial public offering by 2013.

In December 2011, the Saudi prince Alwaleed bin Talal invested 300 million in Twitter. The company was valued at 8.4 billion at the time.

Revenue sources
In July 2009, some of Twitter's revenue and user growth documents were published on TechCrunch after being illegally obtained by Hacker Croll. The documents projected 2009 revenues of US$400,000 in the third quarter and US$4 million in the fourth quarter along with 25 million users by the end of the year. The projections for the end of 2013 were US$1.54 billion in revenue, US$111 million in net earnings, and 1 billion users. No information about how Twitter planned to achieve those numbers was published. In response, Twitter co-founder Biz Stone published a blog post suggesting the possibility of legal action against the hacker.

On April 13, 2010, Twitter announced plans to offer paid advertising for companies that would be able to purchase "promoted tweets" to appear in selective search results on the Twitter website, similar to Google Adwords' advertising model. As of April 13, Twitter announced it had already signed up a number of companies wishing to advertise including Sony Pictures, Red Bull, Best Buy, and Starbucks.

To continue their advertising campaign, Twitter announced on March 20, 2012, that it would be bringing its promoted tweets to mobile devices. Twitter generated US$139.5 million in advertising sales during 2011 and expects this number to grow 86.3% to US$259.9 million in 2012.

The company generated US$45 million in annual revenue in 2010, after beginning sales midway through that year. The company operated at a loss through most of 2010. Revenues were forecast for US$100 million to US$110 million in 2011. Users' photos can generate royalty-free revenue for Twitter, with an agreement with WENN being announced in May 2011. In June 2011, Twitter announced that it would offer small businesses a self serve advertising system.

Implementation
Great reliance is placed on open-source software. The Twitter Web interface uses the Ruby on Rails framework, deployed on a performance enhanced Ruby Enterprise Edition implementation of Ruby.

As of April 6, 2011, Twitter engineers confirmed they had switched away from their Ruby on Rails search-stack, to a Java server they call Blender.

From spring 2007 to 2008 the messages were handled by a Ruby persistent queue server called Starling, but since 2009 implementation has been gradually replaced with software written in Scala. The service's application programming interface (API) allows other web services and applications to integrate with Twitter.

Individual tweets are registered under unique IDs using software called snowflake and geolocation data is added using 'Rockdove'. The URL shortner t.co then checks for a spam link and shortens the URL. The tweets are stored in a MySQL database using Gizzard and acknowledged to users as having been sent. They are then sent to search engines via the Firehose API. The process itself is managed by FlockDB and takes an average of 350 ms.

Interface
On April 30, 2009, Twitter adjusted its web interface, adding a search bar and a sidebar of "trending topics" — the most common phrases appearing in messages. Biz Stone explains that all messages are instantly indexed and that "with this newly launched feature, Twitter has become something unexpectedly important – a discovery engine for finding out what is happening right now."

In March 2012, Twitter became available in Arabic, Farsi, Hebrew and Urdu, the first right-to-left language versions of the site. About 13,000 volunteers helped with translating the menu options. In August 2012, beta support for Basque, Czech and Greek was added, making the site available in 33 different languages.

Outages
When Twitter experiences an outage, users see the "fail whale" error message image created by Yiying Lu, illustrating eight orange birds using a net to hoist a whale from the ocean captioned "Too many tweets! Please wait a moment and try again."

Twitter had approximately ninety-eight percent uptime in 2007 (or about six full days of downtime). The downtime was particularly noticeable during events popular with the technology industry such as the 2008 Macworld Conference & Expo keynote address.


 * May 2008 – Twitter's new engineering team made architectural changes to deal with the scale of growth. Stability issues resulted in down time or temporary feature removal.
 * August 2008 – Twitter withdrew free SMS services from users in the United Kingdom and for approximately five months instant messaging support via a XMPP bot was listed as being "temporarily unavailable".
 * October 10, 2008 – Twitter's status blog announced that instant messaging (IM) service was no longer a temporary outage and needed to be revamped. It was announced that Twitter aims to return its IM service pending necessary major work.
 * June 12, 2009 – In what was called a potential "Twitpocalypse", the unique numerical identifier associated with each tweet exceeded the limit of 32-bit signed integers (2,147,483,647 total messages). While Twitter itself was not affected, some third-party clients could no longer access recent tweets. Patches were quickly released, though some iPhone applications had to wait for approval from the App Store.
 * June 25, 2009 – Twitter ran slowly for some time after over 50,000 tweets on Michael Jackson’s death were recorded in an hour.
 * August 6, 2009 – Twitter and Facebook suffered from a denial-of-service attack, causing the Twitter website to go offline for several hours. It was later confirmed that the attacks were directed at one pro-Georgian user around the anniversary of the 2008 South Ossetia War, rather than the sites themselves.
 * September 22, 2009 – The identifier exceeded the limit for 32-bit unsigned integers (4,294,967,296 total messages) again breaking some third-party clients.
 * December 17, 2009 – A hacking attack replaced the website's welcoming screen with an image of a green flag and the caption "This site has been hacked by Iranian Cyber Army" for nearly an hour. No connection between the hackers and Iran has been established.
 * June–July 2010 – Twitter had a very high service rejection rate (10–20%) during the 2010 FIFA World Cup period, also, the response latency increased substantially.
 * November 2010 – A number of accounts encountered a fault that resulted in them seeing the "fail whale" when they tried to login to their accounts. The accounts themselves were not locked out as account holders could still see their "mentions" page, and post from there, but the timeline and a number of other features were unavailable during this outage.
 * June 21, 2012 – The site was down for around one hour and forty minutes, with the cause being described by Twitter as a "cascading bug".
 * July 26, 2012 – Twitter users in the UK could not post messages for part of the day in advance of the 2012 Summer Olympics.

Privacy and security
Twitter messages are public but users can also send private messages. Twitter collects personally identifiable information about its users and shares it with third parties. The service reserves the right to sell this information as an asset if the company changes hands. While Twitter displays no advertising, advertisers can target users based on their history of tweets and may quote tweets in ads directed specifically to the user.

A security vulnerability was reported on April 7, 2007, by Nitesh Dhanjani and Rujith. Since Twitter used the phone number of the sender of an SMS message as authentication, malicious users could update someone else's status page by using SMS spoofing. The vulnerability could be used if the spoofer knew the phone number registered to their victim's account. Within a few weeks of this discovery Twitter introduced an optional personal identification number (PIN) that its users could use to authenticate their SMS-originating messages.

On January 5, 2009, 33 high-profile Twitter accounts were compromised after a Twitter administrator's password was guessed by a dictionary attack. Falsified tweets — including sexually explicit and drug-related messages — were sent from these accounts.

Twitter launched the beta version of their "Verified Accounts" service on June 11, 2009, allowing famous or notable people to announce their Twitter account name. The home pages of these accounts display a badge indicating their status.

In May 2010, a bug was discovered by İnci Sözlük, involving users that allowed Twitter users to force others to follow them without the other users' consent or knowledge. For example, comedian Conan O'Brien's account, which had been set to follow only one person, was changed to receive nearly 200 malicious subscriptions.

In response to Twitter's security breaches, the US Federal Trade Commission brought charges against the service which were settled on June 24, 2010. This was the first time the FTC had taken action against a social network for security lapses. The settlement requires Twitter to take a number of steps to secure users' private information, including maintenance of a "comprehensive information security program" to be independently audited biannually.

On December 14, 2010, the United States Department of Justice issued a subpoena directing Twitter to provide information for accounts registered to or associated with WikiLeaks. Twitter decided to notify its users and said in a statement, "...it's our policy to notify users about law enforcement and governmental requests for their information, unless we are prevented by law from doing so".

A "MouseOver" exploit occurred on September 21, 2010, when an XSS Worm became active on Twitter. When an account user held the mouse cursor over blacked-out parts of a tweet, the worm within the script would automatically open links and re-post itself on the reader's account. The exploit was then re-used to post pop-up ads and links to pornographic sites. The origin is unclear but Pearce H. Delphin (known on Twitter as @zzap) and a Scandinavian developer, Magnus Holm, both claim to have modified the exploit of a user, possibly Masato Kinugawa, who was using it to create coloured Tweets. Kinugawa, a Japanese developer, reported the XSS vulnerability to Twitter on August 14. Later, when he found it was exploitable again, he created the account 'RainbowTwtr' and used it to post coloured messages. Delphin says he exposed the security flaw by tweeting a JavaScript function for "onMouseOver", and Holm later created and posted the XSS Worm that automatically re-tweeted itself. Security firm Sophos reported that the virus was spread by people doing it for "fun and games", but noted it could be exploited by cybercriminals. Twitter issued a statement on their status blog at 13:50 UTC that "The exploit is fully patched". Twitter representative Carolyn Penner said no charges would be pressed.

In May 2011, a claimant known as "CTB" (subsequently identified as Ryan Giggs) in the case of CTB v Twitter Inc., Persons Unknown took legal action at the High Court of Justice in London against Twitter., requesting that Twitter release details of account holders. This followed gossip posted on Twitter about Giggs' private life, causing conflict relating to privacy injunctions. Tony Wang, the head of Twitter in Europe, said that people who do "bad things" on the site would need to defend themselves under the laws of their own jurisdiction in the event of controversy, and that the site would hand over information about users to the authorities when it was legally required to do so. He also suggested that Twitter would accede to a UK court order to divulge names of users responsible for "illegal activity" on the site.

On May 29, 2011, it was reported that South Tyneside council in England had successfully taken legal action against Twitter in a court in California, which forced Twitter to reveal the details of five user accounts. The council was trying to discover the identity of a blogger called "Mr Monkey" who allegedly posted libellous statements about three local councillors.

On January 23, 2012, it was reported that Twitter would be acquiring Dasient, a startup that offers malware protection for businesses. Twitter hopes that Dasient will help remove hateful advertisers on the website.

On January 26, 2012, Twitter began offering a feature which would allow tweets to be removed selectively by country. Twitter cited France and Germany as examples, where pro-Nazi content is illegal. Previously, deleted tweets were removed in all countries. The first use of the policy was to block the account of German neo-Nazi group Besseres Hannover on October 18, 2012. The policy was used again the following day to remove anti-Semitic French tweets with the hashtag #unbonjuif ("a good jew").

On February 20, 2012, a third-party public-key encryption app (written in Python and partially funded by a grant from the Shuttleworth Foundation ) for private messaging in Twitter, CrypTweet, was released.

On May 17, 2012, Twitter announced it would implement the "Do Not Track" privacy option, a cookie-blocking feature found in Mozilla's Firefox browser. The "Do Not Track" feature works only on sites that have agreed to the service.

In August 2012 it was reported that there is a market in fake Twitter followers that are used to increase politicians' and celebrities' apparent popularity.

Open source
Twitter released several open source projects developed while overcoming technical challenges of their service. Notable projects are the Gizzard Scala framework for creating distributed datastores and the distributed graph database FlockDB.

Innovators patent agreement
On April 17, 2012, Twitter announced it would implement an “Innovators Patent Agreement” which would obligate Twitter to only use its patents for defensive purposes. The agreement will go into effect later 2012.

URL shortener
t.co is a URL shortening service created by Twitter. It is only available for links posted to Twitter and not available for general use. All links posted to Twitter use a t.co wrapper. Twitter hopes that the service will be able to protect users from malicious sites, and will use it to track clicks on links within tweets.

Having previously used the services of third parties TinyURL and bit.ly, Twitter began experimenting with its own URL shortening service for private messages in March 2010 using the twt.tl domain, before it purchased the t.co domain. The service was tested on the main site using the accounts @TwitterAPI, @rsarver and @raffi. On September 2, 2010, an email from Twitter to users said they would be expanding the roll-out of the service to users. On June 7, 2011, Twitter announced that it was rolling out the feature.

Integrated photo-sharing service
On June 1, 2011, Twitter announced its own integrated photo-sharing service that enables users to upload a photo and attach it to a Tweet right from Twitter.com. Users now also have the ability to add pictures to Twitter's search by adding hashtags to the tweet. Twitter also plans to provide photo galleries designed to gather and syndicate all photos that a user has uploaded on Twitter and third-party services such as TwitPic.

Use and social impact


Twitter has been used for a variety of purposes in many industries and scenarios. For example, it has been used to organize protests, sometimes referred to as "Twitter Revolutions", which include the 2011 Egyptian revolution, 2010–2011 Tunisian protests, 2009–2010 Iranian election protests, and 2009 Moldova civil unrest. The governments of Iran and Egypt blocked the service in retaliation. The Hill on February 28, 2011 described Twitter and other social media as a "strategic weapon ... which have the apparent ability to re-align the social order in real time, with little or no advanced warning." During the Arab Spring in early 2011, the number of hashtags mentioning the uprisings in Tunisia and Egypt increased. A study by the Dubai School of Government found that only 0.26% of the Egyptian population, 0.1% of the Tunisian population and 0.04% of the Syrian population are active on Twitter.

The service is also used as a form of civil disobedience: in 2010, users expressed outrage over the Twitter Joke Trial by making obvious jokes about terrorism; and in the British privacy injunction debate in the same country a year later, where several celebrities who had taken out anonymised injunctions, most notably the Manchester United player Ryan Giggs, were identified by thousands of users in protest to traditional journalism being censored.

Another, more real time and practical use for Twitter exists as an effective de facto emergency communication system for breaking news. It was neither intended nor designed for high performance communication, but the idea that it could be used for emergency communication certainly was not lost on the originators, who knew that the service could have wide-reaching effects early on when the San Francisco, California company used it to communicate during earthquakes.

Twitter has been adopted as a communication and learning tool in educational settings mostly in colleges and universities. It has been used as a backchannel to promote student interactions, especially in large-lecture courses. Research has found that using Twitter in college courses helps students communicate with each other and faculty, promotes informal learning, allows shy students a forum for increased participation, increases student engagement, and improves overall course grades.

In May 2008, The Wall Street Journal wrote that social networking services such as Twitter "elicit mixed feelings in the technology-savvy people who have been their early adopters. Fans say they are a good way to keep in touch with busy friends. But some users are starting to feel 'too' connected, as they grapple with check-in messages at odd hours, higher cellphone bills and the need to tell acquaintances to stop announcing what they're having for dinner."

Tech writer Bruce Sterling opined in 2007 that using Twitter for "literate communication" is "about as likely as firing up a CB radio and hearing some guy recite the Iliad". In September 2008, the journalist Clive Thompson mused in a The New York Times Magazine editorial that the service had expanded narcissism into "a new, supermetabolic extreme—the ultimate expression of a generation of celebrity-addled youths who believe their every utterance is fascinating and ought to be shared with the world." Conversely, Vancouver Sun columnist Steve Dotto opined that part of Twitter's appeal is the challenge of trying to publish such messages in tight constraints, and Jonathan Zittrain, professor of Internet law at Harvard Law School, said that "the qualities that make Twitter seem inane and half-baked are what makes it so powerful".

Novelist Rick Moody wrote a short story for Electric Literature called "Some Contemporary Characters," composed entirely of tweets.

In 2009, Nielsen Online reported that Twitter has a user retention rate of forty percent. Many people stop using the service after a month, therefore the site may potentially reach only about ten percent of all Internet users. In 2009, Twitter won the "Breakout of the Year" Webby Award. During a February 2009 discussion on National Public Radio's Weekend Edition, the journalist Daniel Schorr stated that Twitter accounts of events lacked rigorous fact-checking and other editorial improvements. In response, Andy Carvin gave Schorr two examples of breaking news stories that played out on Twitter and said users wanted first-hand accounts and sometimes debunked stories. On November 29, 2009 Twitter was named the Word of the Year by the Global Language Monitor, declaring it "a new form of social interaction". Time magazine acknowledged its growing level of influence in its 2010 Time 100; to determine the influence of people, it used a formula based on famous social networking sites, Twitter and Facebook. The list ranges from Barack Obama and Oprah Winfrey to Lady Gaga and Ashton Kutcher.

During the 2012 Summer Olympics opening ceremony, in which he appeared at the London Olympic Stadium in person, Sir Tim Berners-Lee, the founder of the World Wide Web, tweeted "This is for everyone", which was instantly spelled out in LCD lights attached to the chairs of the 80,000 people in the audience.

According to an analysis of accounts, the heads of state of 125 countries and 139 other leading politicians have Twitter accounts that have between them sent more than 350,000 tweets and have almost 52 million followers. However, only 30 of these do their own tweeting, more than 80 do not subscribe to other politicians and many do not follow any accounts.

After claims in the media that the hashtags #wikileaks and #occupywallstreet were being censored because they did not show up on the site's list of trending topics, Twitter responded by stating that it does not censor hashtags unless they contain obscenities.

Television, rating
Twitter is also increasingly used for making TV more interactive and social. This effect is sometimes referred to as the "virtual watercooler" or social television — the practice has been called "chatterboxing". Twitter has been successfully used to encourage people to watch live TV events, such as the Oscars, the Super Bowl and the MTV Video Music Awards; however this strategy has proven less effective with regularly scheduled TV shows. Such direct cross-promotions have been banned from French television due to regulations against secret advertising.

In December 2012, Twitter and Nielsen entered a multi-year agreement to produce social TV ratings, which are expected to be commercially available for the fall 2013 season as the Nielsen Twitter TV Rating. Advertising Age said Twitter had become the new TV Guide. Then in February 2013, Twitter acquired Bluefin Labs for an estimated US$50 million to $100 million, which was the company's largest acquisition as of 2013. Founded in 2008 at the MIT Media Lab, Bluefin is a data miner whose analysis tells which brands (e.g., TV shows and companies) are chatted about the most in social media. MIT Technology Review said that Bluefin gives Twitter part of the US$72 billion television advertising market.

Most popular accounts
As of December 2012, the ten accounts with the most followers belonged to the following individuals and organisations:
 * 1) Lady Gaga (32,049,140 followers worldwide)
 * 2) Justin Bieber (31,377,695)
 * 3) Katy Perry (29,977,472)
 * 4) Rihanna (27,230,980)
 * 5) Barack Obama (24,418,534) - highest ranked account representing a politician
 * 6) Britney Spears (22,451,413)
 * 7) Taylor Swift (21,734,138)
 * 8) YouTube (20,672,560) - highest account not representing an individual
 * 9) Shakira (18,967,476) - highest ranked account based outside the United States
 * 10) Kim Kardashian (16,830,838)

Other selected accounts:
 * 13. Cristiano Ronaldo (14,865,734) - highest account representing an athlete
 * 58. FC Barcelona (7,575,936) - highest account representing a sports team

Record tweets
On February 3, 2013, Twitter announced that a record 24.1 million tweets were sent the night of Super Bowl XLVII.

Reception
In 2006, when Twitter launched under the name "Twttr", Michael Arrington of TechCrunch commented that although he liked the service, he also noted that he felt uncomfortable with the fact that every user's Twitter page is available to the public.

Change of focus
Twitter emphasized its news and information-network strategy in November 2009 by changing the question asked to users for status updates from "What are you doing?" to "What's happening?" Entertainment Weekly put it on its end-of-the-decade, "best-of" list, saying, "Limiting yourself to 140 characters—the maximum for messages on this diabolically addictive social-networking tool—is easy."

On November 22, 2010, Biz Stone, a cofounder of the company, expressed for the first time the idea of a Twitter news network, a concept of a wire-like news service he has been working on for years.