Twitter history timeline: from twttr to X
Twitter's story is usually told through a few famous moments: the first post, the hashtag, the jump to 280 characters, the takeover and the rename. This timeline puts those moments in order with the details in between. Every entry is backed by a source listed at the end of its section, and the same facts feed our history quiz.
2006 to 2008: a side project takes off
March 2006. Jack Dorsey posts "just setting up my twttr". The project lives inside Odeo, a San Francisco podcasting company, and its code name is twttr. The people usually credited as cofounders are Jack Dorsey, Noah Glass, Biz Stone and Evan Williams.
July 15, 2006. The full service opens to the public. Posts are capped at 140 characters because Twitter was designed to work over SMS text messages, which allow 160. Biz Stone later explained that the team reserved the rest for the author's name.
October 2006. Dorsey, Stone and Williams, through their new company Obvious Corporation, acquire Odeo and its assets, Twitter included.
March 2007. South by Southwest Interactive in Austin becomes the breakout moment. Daily posts jump from about 20,000 to about 60,000 during the festival.
August 23, 2007. Chris Messina suggests using the # symbol to group posts, using #barcamp as his example. People start writing hashtags by hand long before Twitter supports them.
September 2007. The term "Fail Whale" appears for Twitter's over-capacity error page, which shows small birds lifting a whale. Outages are common in these years, and the image becomes a symbol of them.
Sources: History of Twitter, Twitter and Hashtag on Wikipedia; NPR, "Twitter Turns Five".
2009 to 2013: features become official
June 2009. Verified accounts launch, with a blue checkmark to help people tell notable accounts from impostors and parodies.
July 2, 2009. Hashtags become clickable links to search results.
November 2009. Twitter begins rolling out an official retweet button. Until then, people retweeted by copying a post and adding "RT @name".
2010. Trending Topics are introduced. During that summer's World Cup, Twitter shows small flags next to country hashtags, the first "hashflags".
2012. Twitter starts linking cashtags such as $AAPL. It buys Vine, a looping six-second video app, in October and introduces Douglas Bowman's simplified bird logo. The bird mascot had long been nicknamed Larry, after the basketball player Larry Bird.
November 7, 2013. Twitter goes public on the New York Stock Exchange under the ticker TWTR.
Sources: Twitter verification, Hashtag, Twitter, Inc. and Vine on Wikipedia; VatorNews on the retweet button, November 2009.
2014 to 2019: hearts, limits and live video
March 2014. Ellen DeGeneres posts a group selfie during the Oscars broadcast. It passes Barack Obama's 2012 election-night photo as the most retweeted post up to that point.
March 2015. Twitter announces it has acquired Periscope, a live video streaming app.
August 2015. The limit for direct messages rises from 140 to 10,000 characters. Public posts stay at 140.
November 3, 2015. The star-shaped "favorite" becomes a heart, and favorites are renamed likes.
2016. Photos and other attached media stop counting against the character limit.
January 2017. Vine shuts down. Uploads had already been switched off in October 2016.
2017. @names that Twitter adds automatically at the start of replies stop counting toward the limit. After a test that began in September, the limit for most languages doubles to 280 in November. Chinese, Japanese and Korean stay at 140, since those scripts pack more meaning into each character.
July 2018. Twitter removes locked accounts, ones frozen over suspected spam or takeover whose owners never confirmed control, from follower counts. Most people lose four followers or fewer; very large accounts lose many more.
Sources: PetaPixel on the Oscars selfie; BetaNews on the DM limit; The Next Web on hearts; CNBC on 280 characters; TechCrunch on the 2018 cleanup.
2020 to 2022: experiments and a sale
November 2020. Fleets, posts that disappear after 24 hours, launch. They are removed in August 2021.
January 2021. Birdwatch, a program that lets users add context notes to misleading posts, starts as a pilot. It is renamed Community Notes in November 2022.
March 31, 2021. Periscope is discontinued.
May 2021. Spaces, live audio rooms, opens to any account with at least 600 followers. It opens to everyone that October.
June 3, 2021. Twitter Blue, the first subscription, launches in Canada and Australia. Its headline feature is Undo Tweet.
November 29, 2021. Jack Dorsey steps down as CEO. Chief technology officer Parag Agrawal replaces him.
October 2022. The edit button begins rolling out to Twitter Blue subscribers. On October 27, Elon Musk completes his purchase of Twitter for about $44 billion, or $54.20 a share. The stock is delisted the next month.
December 2022. View counts start appearing under posts. With the relaunch of Twitter Blue, gold checkmarks mark verified organizations and gray checkmarks mark government accounts.
Sources: Twitter, Twitter, Inc. and Community Notes on Wikipedia; TechCrunch on Spaces; CNN on Twitter Blue; TechCrunch on editing; TechCrunch on view counts.
2023 onward: X
April 2023. Removal of legacy blue checkmarks begins on April 20, after an April 1 deadline slips. Twitter, Inc. is merged into X Corp. the same month.
July 2023. Twitter is rebranded as X. The bird logo is retired after more than a decade.
May 17, 2024. The service's core domain switches from twitter.com to x.com.
March 2025. Musk's artificial intelligence company xAI acquires X in an all-stock deal.
July 2025. Linda Yaccarino, appointed CEO of X Corp. in 2023, resigns.
Sources: Twitter verification, History of Twitter, Twitter and Twitter, Inc. on Wikipedia.
Test yourself
Forty of these facts are in the Twitter history quiz. Each round draws ten, and the answers page explains every one with its source. Tweet Test is an independent fan site with no connection to X Corp.