This is Twitter-land

Twitter, Inc.

Type	Private
Founded	San Francisco, California, United States
Founder	Jack Dorsey Evan Williams Biz Stone
Headquarters	795 Folsom St., Suite 600, San Francisco, CA 94107, United States
Area served	Worldwide
Key people	Jack Dorsey (Chairman) Dick Costolo (CEO) Evan Williams (Product Strategy) Biz Stone (Creative Director)
Revenue	US $150 million (projected 2010)
Employees	300 (2010)
Slogan	What's happening?
Website	twitter.com
Alexa rank	9 (October 2010[update])
Type of site	mobile social network service, microblogging
Registration	Required
Users	190 million (visitors monthly)
Available in	Multilingual English, Spanish, Japanese, German, French, and Italian
Launched	July 15, 2006
	Twitter is a website, owned and operated by Twitter Inc., which offers a social networking and microblogging service, enabling its users to send and read other users' messages called tweets. Tweets are text-based posts of up to 140 characters displayed on the user's profile page. Tweets are publicly visible by default, however senders can restrict message delivery to their friends list. Users may subscribe to other users' tweets—this is known as following and subscribers are known as followers.[7] All users can send and receive tweets via the Twitter website, compatible external applications (such as for smartphones), or by Short Message Service (SMS) available in certain countries.[8] While the service is free, accessing it through SMS may incur phone service provider fees. The website is based in San Francisco, California. Twitter also has servers and offices in San Antonio, Texas and Boston, Massachusetts. Since its creation in 2006 by Jack Dorsey, Twitter has gained popularity worldwide and currently has more than 175 million users.[9] Quantcast estimates Twitter has 54 million monthly unique U.S. visitors. It is sometimes described as the "SMS of the Internet." Technology Implementation The Twitter Web interface uses the Ruby on Rails framework,[65] deployed on a performance enhanced Ruby Enterprise Edition implementation of Ruby.[66] From the spring of 2007 until 2008 the messages were handled by a Ruby persistent queue server called Starling,[67] but since 2009 implementation has been gradually replaced with software written in Scala.[68] The service's application programming interface (API) allows other web services and applications to integrate with Twitter.[69][70] 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."[71] Outages The Twitter fail whale error message. When Twitter experiences an outage, users see the "fail whale" error message image created by Yiying Lu,[72] illustrating several red birds using a net to hoist a whale from the ocean captioned "Too many tweets! Please wait a moment and try again."[73] Twitter had approximately 98% uptime in 2007 (or about six full days of downtime).[74] The downtime was particularly noticeable during events popular with the technology industry such as the 2008 Macworld Conference & Expo keynote address.[75][76] 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 weren't 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 (which remains ongoing). 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[77] and for approximately five months instant messaging support via a XMPP bot was listed as being "temporarily unavailable".[78] 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.[79] 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).[80] 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.[81] September 22, the identifier exceeded the limit for 32-bit unsigned integers (4,294,967,296 total messages) again breaking some third-party clients.[82] August 6, 2009, Twitter and Facebook suffered from a denial-of-service attack, causing the Twitter website to go offline for several hours.[83] 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.[84] 17 December 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.[85]  Privacy and security 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.[86] While Twitter displays no advertising, advertisers can target users based on their history of tweets and may quote tweets in ads[87] 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.[88] 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.[89] On January 5, 2009, 33 high-profile Twitter accounts were compromised after a Twitter administrator's password was guessed by a dictionary attack.[90] Falsified tweets — including sexually explicit and drug-related messages — were sent from these accounts.[91] 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.[92] In May 2010, a bug was discovered by İnci Sözlük users that allowed Twitter users to force others to follow them without the other user's 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.[93] In response to Twitter's security breaches, the 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.[94] "MouseOver" exploit On 21 September 2010, 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.[95] The exploit was then re-used to post pop-up ads and links to pornographic sites. The origin is unclear but Pearce 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.[96] 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.[96] Delphin says he exposed the security flaw by tweeting a JavaScript function for "onMouseOver",[96] and Holm later created and posted the XSS Worm that automatically re-tweeted itself.[95] Accounts affected by the virus included Sarah Brown, wife of former British Prime Minister Gordon Brown. Security firm Sophos reported the virus was spread by people doing it for "fun and games", but noted it could be exploited by cybercriminals.[97] Twitter issued a statement on their status blog at 13:50 UTC that "The exploit is fully patched".[95][98] Twitter representative Carolyn Penner has expressed that they will not be pressing charges over this incident.[99] Open source Twitter released several open source projects developed while overcoming technical challenges of their service.[100] Notable projects are the Gizzard Scala framework for creating distributed datastores and the distributed graph database FlockDB.