As you browse tweets on Twitter, you’re sure to stumble across words prefaced with the “#” symbol. You might know this as the pound sign or the tic-tac-toe board but in Twitter it’s called a hashtag and is used to mark a conversation or event.

A hashtag is simply a word, phrase or string of characters that make Twitter easier to search. If you attend a conference, there might be an official hashtag. The Surrey International Writers’ Conference used #siwc2010. Other hashtags are ongoing discussions for brands (#iPhone), activities (#amwriting) and timeless information (#quotes). Use the search function to find a list of tweets featuring the hashtag of interest.  If you want to join the conversation, simply include the hashtag in your tweet.