Twitter is a social media platform launched in 2006 that allows users to post short messages called tweets. It was co-founded by Jack Dorsey as a side project of podcasting company Odeo to allow users to share short bursts of information. Key features include limiting tweets to 140 characters to promote brevity, and allowing users to follow topics and other users. The platform gained popularity at the 2007 SXSW conference and has since been used widely for personal and commercial purposes like marketing.