2006 March 21st
Jack Dorsey, Noah Glass, Evan Williams and Biz Stone officially launched the social networking and microblogging service Twitter. The social network Twitter allows users to read and send short posts referred to as “tweets”. The length of individual tweets was initially limited to 140 characters. In November 2017, the post limit was doubled to 280 characters.
On 23 August 2007, the first hashtag (#) appeared on Twitter, used by user Chris Messina in a tweet related to the #barcamp conference. Six years after its launch in March 2012, the microblogging service Twitter has reached more than 140 million active users who send 340 million tweets per day.