Technical Twitter abbreviations:
- MT = Modified tweet. This means the tweet you're looking at is a paraphrase of a tweet originally written by someone else.
- RT = Retweet. The tweet you're looking at was forwarded to you by another user.
- DM = Direct message. A direct-message is a message only you and the person who sent it can read. IMPORTANT: To DM someone all you need to type is D username message.
- PRT = Partial retweet. The tweet you're looking at is the truncated version of someone else's tweet.
- HT = Hat tip. This is a way of attributing a link to another Twitter user.
- CC = Carbon-copy. Works the same way as email.
Read more: http://articles.businessinsider.com/2010-08-02/tech/30060587_1_tweet-abbreviations-twitter-user#ixzz1dbkio2bk