Twitter is an online social networking forum. The website was officially launched in July 2006 by Jack Dorsey, Evan Williams, Biz Stone and Noah Glass. Twitter users can either send or read short messages (no more than 140 characters) and upload pictures/videos and all sorts of audio-visual content including web links.
It is a very engaging and entertaining medium that has attracted followers from all over the world in huge numbers. The message posted on Twitter by its registered members is called tweet. Unregistered members can only read tweets but not send it whereas registered ones can send and read.