This document discusses Twitter, including what it is, how it is used, and some examples of its use. Twitter is a social media platform that allows users to post short messages called tweets. Businesses can use Twitter to communicate with customers, get feedback, and advertise. Government agencies also use Twitter to inform the public and communicate during emergencies. Celebrities have large Twitter followings and use it to interact with fans and share details about their lives. The document also discusses trends on Twitter in 2009 and potential dangers of using the platform.