Twitter is a a real-time short messaging service that works over multiple networks and devices. Users have 140 characters to "tweet" their message out to the world, which is picked up on other twitter user's pages, mobile phones, websites, etc.
Twitter can help you reach new customers, make new friends, and communicate in a whole new way. You can integrate Twitter into your website in many useful ways: automated updates via RSS, follow widgets, Twitter directories and much more.