Twitter

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Twitter, Inc.

Type	Private
Founded	2006
Headquarters	San Francisco, California, USA
Key people	Jack Dorsey, Chairman Evan Williams, CEO Biz Stone, Creative Director
Industry	mobile social network service, micro-blogging
Website	http://twitter.com/

Twitter is a free social networking and micro-blogging service that enables its users to send and read other users' updates known as tweets. Tweets are text-based posts of up to 140 characters in length which are displayed on the user's profile page and delivered to other users who have subscribed to them (known as followers). Senders can restrict delivery to those in their circle of friends or, by default, allow anybody to access them. Users can send and receive tweets via the Twitter website, Short Message Service (SMS) or external applications. The service is free to use over the Internet, but using SMS may incur phone service provider fees.

Since its creation in 2006, Twitter has gained extensive notability and popularity worldwide. It is often described as the "SMS of Internet," in that the site provides the functionality (via its application programming interfaces) for other desktop and web-based applications to send and receive short text messages, often obscuring the Twitter service itself.

Four gateway numbers are currently available for SMS — short codes for the United States, Canada, India, and a United Kingdom-based number for international use. There is also a short code for Vodafone users from the UK. Several third parties offer posting and receiving updates via e-mail.

Estimates of the number of daily users vary as the company does not release the number of active accounts. In November 2008, Jeremiah Owyang of Forrester Research estimated that Twitter had 4-5 million users. A February 2009 Compete.com blog entry ranks Twitter as the third most used social network (Facebook being the largest, followed by MySpace), which puts the number of unique monthly visitors at roughly 6 million and the number of monthly visits at 55 million.In March 2009, a Nielsen.com blog ranked Twitter as the fastest growing site in the Member Communities category for February 2009. Twitter had a growth of 1382%, Zimbio had a growth of 240%, followed by Facebook with a growth of 228%.

Technology

Twitter has been described as akin to a web-based IRC client. The Twitter web interface uses the Ruby on Rails framework.From the spring of 2007 until sometime in 2008 the actual messages were handled by a pure-Ruby persistent queue server called Starling.Starling was replaced in 2008 with Scarling, a persistent queue server written in the Scala programming language, which has since been renamed Kestrel.The Twitter API itself allows the integration of Twitter with other web services and applications.In late April 2008, TechCrunch reported that, due to downtime related to scaling problems, Twitter would abandon Ruby on Rails as their web framework and create a new system with PHP or Java. Evan Williams, however, soon debunked this report in a Tweet he sent on May 1, 2008.

Twitter messages may be tagged using hashtags, a word or phrase prefixed with a #, such as #beer.This enables tweets on a specific subject to be found by simply searching for their common hashtag, provided that the user has tagged his or her tweet. Meanwhile, the @ sign before a username, such as @example, is used to distinguish a reply directed at that user. A message preceded by the @username prefix can still be read by anyone, but is treated as directed firstly to the user in question.

Privacy and security

Twitter collects personally identifiable information about its users and shares it with third parties. Twitter considers that information an asset, and reserves the right to sell it if the company changes hands.

A security vulnerability was reported on April 7, 2007, by Nitesh Dhanjani and Rujith. The problem was due to Twitter's using the SMS message originator as the authentication of the user's account. Nitesh used FakeMyText to spoof a text message, whereupon Twitter posted the message on the victim's page.This vulnerability can only be used if the target's phone number is known.Within a few weeks of this discovery Twitter introduced an optional PIN that its users can specify to authenticate SMS-originating messages.

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