Hashtag

From Tech Tarts Wiki

A hashtag was created by the Twitter community to group tweets and add extra information by tagging it with the hash or pound symbol #. It is similar to a web tag you see on blogs and picture sites. To add a hashtag to a tweet you want grouped to a category simply put the hashtag before the word, for example #techtarts, if you want people looking for the category techtarts to find your twitter post.