Twitter is a microblogging platform that allows users to post short updates called tweets that are up to 140 characters. Users can follow other users on Twitter to receive their tweets, and other users can choose to follow them as well. Unlike on Facebook, following is not necessarily reciprocal on Twitter. Twitter has grown rapidly since 2008 to over 20 million users, gaining about 10,000 new users per day. Organizations can use Twitter in passive, active, and hybrid ways to engage with audiences and disseminate information. Common uses include live tweeting events, press conferences, and facilitating online discussions through hashtags.