Tweet: A message of up to 140 characters you post as your status update for your followers to see.
Twitter handle: Your twitter username is also known as your handle. An “at” symbol (@) always preceds a twitter handle, which makes it clickable on Twitter. For example, my Twitter handle is @geekhibrid, so anyone who wants to send me a direct Tweet would begin the message with my handle.
Retweet, AKA RT: When you forward a tweet from someone else to your followers, this is known as a retweet and should begin with RT so that followers know what you’re doing:
RT @geekhibrid: how to create a media sheet for radio interviews (link)
Direct message, AKA DM: This is a direct message that you send to someone’s Twitter Inbox, which is the equivalent of email on Twitter.
Hashtag: Placing a hashtag (also known as a pound sign “#”) in front of a word improves the word’s track-ability in Twitter search and makes it clickable. For example, if you are giving away a free report, you might include #freereport in your tweet so that you can easily search to find post with this reference. Hashtags are also useful for helping your content show up when people search.