Twitter, the 140-character messaging service favored by everyone from US President Barack Obama to the Pope, began as a side-project but rapidly morphed into one of the most powerful sociocultural sensations of our time.
After eight years of explosive user growth marred by persistent technical challenges and management shake-ups, Twitter is now preparing to go public in Silicon Valley's largest initial public offering since Facebook Inc's last year.
March 21, 2006: Co-founder Jack Dorsey sends the first tweet: "just setting up my twttr."
Twitter is a side project within Odeo, a struggling podcasting company where Dorsey worked as a software engineer alongside Twitter co-creators Noah Glass and Biz Stone. The length of tweets are capped at 140 characters in order to include a user's name and still fit within the 160-character SMS messaging format used by mobile phones.
October 25, 2006: Evan Williams, CEO of Odeo, forms a company called Obvious Corp, which acquires all of Odeo's assets, including Twitter.
March 2007: Twitter stages a big promotion at the South by Southwest conference in Austin, Texas, lining the hallways with flat-screen panels that display a constant stream of Twitter messages. The service gains a loyal following among influential bloggers and tech enthusiasts that will prove key to its future growth.
April 2007: Twitter is spun out as a separate company, with co-founders Dorsey, Williams and Biz Stone. Dorsey is appointed CEO.
March 2008: Twitter has 1.3 million users, according to media reports at the time.
October 2008: Williams replaces Dorsey as Twitter CEO. Dorsey, who becomes Twitter Chairman but is no longer a Twitter employee, later recalls in Vanity Fair magazine that it felt like he was "punched in the stomach."
November 2008: Twitter rebuffs a $500 million acquisition offer by social networking powerhouse Facebook, according to media reports. Twitter has about six million registered users around this time.
April 2009: Oprah Winfrey joins Twitter. Ashton Kutcher becomes first celebrity to amass 1 million followers on Twitter. Twitter's total number of registered users reached 14 million the previous month.
June 2009: The U.S. State Department asks Twitter to delay a planned upgrade to its system that would have cut daytime service