Twitter is a microblogging service that allows users to post and read text-based tweets of up to 140 characters. Tweets are displayed on user profiles and delivered to followers, and the platform supports online communication through features like public tweets, direct messages between followers, hashtags to group topics, and applications for managing accounts. The profile, tweets, direct messages, hashtags, and third-party tools like TweetDeck and HootSuite are some of the basic building blocks for using Twitter to engage with others through sharing content, links, humor and daily activities.