Every phenomenon that spreads quickly around the world must come complete with its own lexicon of slang. Being a heavily text-based phenomenon, Twitter is perhaps a more complete example of this than any other. Starting with the practice of writing a message on Twitter, or "Tweeting", this slang refers to a great deal of other topics as well. If you wish to send a message to one specific user, you use the @ symbol followed by their ID, and this is known as an "at-reply". If they do not wish for this message to show up in their feed for the notice of other users, they may send it as a direct message, or simply "DM". 

Of course one of the most commonly used pieces of slang is "re-tweeting", which is largely self-explanatory, referring as it does to the practice of copying and crediting the "tweet" of another user. It is not dissimilar to a chain e-mail. Then there is the list of tweets that you read from fellow users. The tweets themselves turn up in what is known as your "feed". Your feed will be particularly busy if you "follow" a lot of people - which is the fairly obvious slang for reading their tweets. 

A piece of slang which is not limited to Twitter but has found its natural home there is "Crowdsourcing". This refers to asking a question or requesting a favor via Twitter which, when read by your followers, will gain you a lot of information or help from a number of people - or a crowd.