Twitter was originally called “twttr,” a name inspired by the sound of birds chirping, and the first tweet was sent by Jack Dorsey on March 21, 2006, reading “just setting up my twttr.” ¹⁾

The 140-character limit was chosen because tweets needed to fit within the 160-character SMS messaging format used by mobile phones, leaving room for a user's name. ²⁾

The name “Twitter” came from Noah Glass and the Oxford English Dictionary definition: “a short inconsequential burst of information, chirps from birds.” ³⁾

Twitter began as a side project within Odeo, a struggling podcasting company where Jack Dorsey worked as a software engineer alongside Noah Glass and Biz Stone. ⁴⁾

Twitter's popularity exploded at the 2007 South by Southwest Interactive festival in Austin, Texas, where the company placed large screens in conference hallways displaying live tweets, tripling daily usage by week's end. ⁵⁾

The hashtag (#) was proposed by user Chris Messina in 2007 as a way to group posts, becoming one of Twitter's most defining features. ⁶⁾

Retweeting was not created by Twitter itself but by its users, who initially copied text and typed “RT” before the feature was officially automated in November 2009. ⁷⁾

Chris Wetherell, the developer who built the retweet button in 2009, later likened it to “handing a four-year-old a loaded weapon,” saying no one at Twitter anticipated how it would alter the platform. ⁸⁾

In November 2008, Twitter rebuffed a $500 million acquisition offer from Facebook, when Twitter had about six million registered users. ⁹⁾

In April 2009, Ashton Kutcher became the first celebrity to amass 1 million followers on Twitter, beating CNN's breaking news feed in a highly publicized race. ¹⁰⁾

In June 2009, the US State Department asked Twitter to delay a planned upgrade that would have cut daytime service in Iran, underscoring the platform's growing geopolitical importance during protests. ¹¹⁾

Twitter introduced its verification system in 2009 after celebrities including Kanye West and baseball manager Tony La Russa complained about impersonator accounts. ¹²⁾

In 2016, Twitter opened up the verification process for anyone to apply, a significant change from its original invitation-only system. ¹³⁾

In January 2009, an eyewitness tweeted a photo of US Airways Flight 1549 passengers standing on the wing after the plane landed in the Hudson River, cementing Twitter's status as a real-time news platform. ¹⁴⁾

The famous “fail whale” image greeted users whenever Twitter was overloaded, becoming a defining symbol of the platform's early technical struggles. ¹⁵⁾

Twitter's first version was built using the Ruby programming language through the Ruby on Rails framework, with all data stored on MySQL. ¹⁶⁾

Twitter began migrating away from Ruby on Rails in 2009 and completed the switch to a Java server called Blender in April 2011, achieving better scalability than initially expected. ¹⁷⁾

Between June 2008 and June 2009, Twitter experienced 1,444% growth, with average time spent on the site also up 175%. ¹⁸⁾

Twitter finalized its IPO share price at $26 in November 2013, raising $1.82 billion and giving the company a market valuation of about $14 billion. ¹⁹⁾

At the time of its 2013 IPO, Twitter's offering was the second-biggest internet IPO of all time, behind Facebook but ahead of Google. ²⁰⁾

At the time of its IPO in 2013, Twitter had 230 million monthly active users and 100 million daily active users, with 500 million tweets published daily. ²¹⁾

Twitter bought Vine in 2012 for a reported $30 million, and although it shut down in 2017, the six-second video app helped shape today's short-form video culture. ²²⁾

Twitter acquired TweetDeck in 2011 for approximately $20.4 million, one of its earliest major acquisitions. ²³⁾

Twitter's largest acquisition was a $479 million stock purchase to acquire TellApart in 2015. ²⁴⁾

Twitter acquired Magic Pony Technology in 2016 for $150 million to improve image processing and machine learning capabilities. ²⁵⁾

In 2016, Twitter received acquisition offers from Alphabet, Microsoft, Salesforce, Verizon, and Disney, all of which were withdrawn partly due to concerns about abuse and harassment on the platform. ²⁶⁾

Twitter expanded its iconic 140-character limit to 280 characters in 2017, along with introducing an algorithmic timeline. ²⁷⁾

Evan Williams replaced Jack Dorsey as CEO in 2008; Dick Costolo took over in 2010; and Dorsey returned as CEO in 2015. ²⁸⁾

When Dick Costolo joined Twitter as Chief Operating Officer in September 2009, he started his new job by tweeting: “Task #1: undermine CEO, consolidate power.” ²⁹⁾

In September 2009, Twitter raised $100 million in funding in a deal that valued the company at $1 billion. ³⁰⁾

In April 2010, Twitter announced a test of “promoted tweets,” its first advertising product, with six advertising partners including Starbucks and Virgin America. ³¹⁾

In December 2011, Saudi Prince Alwaleed bin Talal bought a $300 million stake in Twitter by purchasing shares from existing investors, valuing the company at roughly $8 billion. ³²⁾

The original Twitter blue bird logo was designed by Martin Grasser, who intended it to be “simple, balanced, and legible at very small sizes.” ³³⁾

Elon Musk's connection to the letter X goes back 24 years to when he founded X.com, which was later renamed PayPal despite his objections. ³⁴⁾

The new X logo was projected onto the facade of Twitter's San Francisco headquarters on the night of July 23, 2023, when the rebranding was announced. ³⁵⁾

Twitter was rebranded as X in July 2023, replacing the iconic blue bird logo with a white X on a black background, with Musk describing the logo as “minimalist art deco.” ³⁶⁾

In April 2023, the company's corporate parent changed its name from Twitter, Inc. to X Corp., several months before the platform itself was renamed X. ³⁷⁾

Elon Musk acquired Twitter for $44 billion in October 2022, after initially offering $43.4 billion ($54.20 per share) in April 2022. ³⁸⁾

In July 2022, Twitter sued Elon Musk for violating his deal, asking a Delaware court to order him to complete the merger. ³⁹⁾

Between June 2022 and February 2023, antisemitic posts on X doubled, according to research by the Institute for Strategic Dialogue. ⁴⁰⁾

In November 2023, Musk endorsed an antisemitic post on X that falsely claimed members of the Jewish community were stoking hatred against white people. ⁴¹⁾

X's daily user base dropped 10% in the year leading up to Linda Yaccarino stepping down as CEO in 2025, falling to 217 million daily users according to Sensor Tower. ⁴²⁾

X users spend an average of 31 minutes per day on the platform, compared to just eight minutes per day for Threads users. ⁴³⁾

Despite user declines, X remains 65% bigger than Instagram's Threads and 10 times larger than Bluesky when it comes to daily users. ⁴⁴⁾

In March 2025, X was acquired by xAI, Elon Musk's artificial intelligence platform, in a deal valuing it at $33 billion. ⁴⁵⁾

Among the earlier popular hashtags was #uknowurblackwhen, coined by user Ashley Weatherspoon, which New York Times critic James Poniewozik described as “a sort of origin story for Black Twitter.” ⁴⁶⁾

Twitter became a platform where women shared frank accounts of sexual harassment and assault, fueling the #MeToo movement. ⁴⁷⁾

In May 2009, a message from space was sent via Twitter, adding to the platform's list of historic firsts. ⁴⁸⁾

X's full-archive search API provides complete access to the full corpus of X data dating back to the first post in March 2006. ⁴⁹⁾

Twitter was initially programmed using Ruby on Rails by Jack Dorsey and Florian, with Noah Glass managing and Biz Stone handling design. ⁵⁰⁾

By December 2012, Twitter had reached 200 million monthly active users. ⁵¹⁾