Twitter 101 provides an overview of Twitter and how businesses can use it. Twitter allows micro-blogging of tweets up to 140 characters. Most Twitter users are aged 25-54, with the largest segment being 45-54. Businesses can use Twitter to develop brands, interact with customers, track brand conversations, promote events, and build relationships with journalists. The document outlines how to set up a Twitter profile and engage an audience through following others, searching, and using applications to organize profiles.