A free social messaging tool that lets people stay connected through brief text message updates up to 140 characters in length. Twitter is based on you answering the question "What are you doing?" You then post thoughts, observations, and goings-on during the day. Your update is posted on your Twitter profile page through SMS text messaging, the Twitter Web site, instant messaging, RSS, e-mail, or through other social applications and sites, such as Facebook.
See "Cool Twitter Tools for Better Tweeting" in the Did You Know...? section of Webopedia.
See also "Social Media Tips for Online Marketing Plus 30 Social Media Sites" in the Did You Know...? section of Webopedia.