This document provides an introduction and overview of the social media platform Twitter. It describes Twitter as a microblogging service that allows users to post short updates of up to 140 characters. Key aspects of Twitter discussed include hashtags for labeling tweets, following other users to see their updates, public @replies and private direct messages between users, retweeting others' posts, and searching for content on Twitter. The document encourages learning more about how to sign up and get started using Twitter.