Twitter is a free social networking and micro-blogging service that allows its users to send and read other users' updates (otherwise known as tweets), which are text-based posts of up to 140 characters in length.
Updates are displayed on the user's profile page and delivered to other users who have signed up to receive them. The sender can restrict delivery to those in his or her circle of friends (delivery to everyone being the default). Users can receive updates via the Twitter website, instant messaging, SMS, RSS, email or through an application such as Twitterrific or Facebook. As of July 2008, over 2,200,000 accounts were registered.
Here is a video for those of you that want to see what Twitter is in plain english,
Do you tweet? if so, add me @UrbanJibaro