X, formerly known as Twitter, is an American microblogging and social networking service. It is one of the world's largest social media platforms and one of the most-visited websites. Users can share short text messages, images, and videos in short posts (commonly and unofficially known as "tweets") and like other users' content. The platform also includes direct messaging, video and audio calling, bookmarks, lists, communities, Grok chatbot integration, job search, and a social audio feature (X Spaces). Users can vote on context added by approved users using the Community Notes feature.
The platform, then called twttr, was created in March 2006 by Jack Dorsey, Noah Glass, Biz Stone, and Evan Williams, and was launched in July of that year; it was renamed Twitter some months later. Twitter grew quickly; by 2012 more than 100 million users produced 340 million daily tweets. Twitter, Inc., was based in San Francisco, California, and had more than 25 offices around the world. A signature characteristic of the service initially was that posts were required to be brief. Posts were initially limited to 140 characters, which was changed to 280 characters in 2017. The limitation was removed for subscribed accounts in 2023. 10% of users produce over 80% of tweets. In 2020, it was estimated that approximately 48 million accounts (15% of all accounts) were run by internet bots rather than humans.