Tweet - a Twitter single update of 140 characters.
RT - Retweet. Reposting a tweet from someone else. This is a good thing and shows you are human instead of an automated program.
Tweetups - Using Twitter to meet with other Twitter folks in person.
TTs - trending topics are a range of subjects which many users across Twitter are talking about simultaneously. (An example of this would be the Superbowl, the killing of Bin Laden, the Presidential debates or #Celtics, #socialmedia,)
Twit Validation Service - a service tht validates the user is a real person and not automated.
@username - directs a conversation to a particular person but is available for all of your followers to see.
DM or DT - a private (direct) tweet. Direct tweets are private and do not appear in the public timeline.
#topic - called a hashtag, this is a way to group tweets by a keyword. This is particularly helpful for events and groups.
#ff - a nice way to promote your Twitter friends for others to see and follow on Fridays.
Twitter in a Nutshell
1. Check and participate in Twitter every day
2. Post what you would like to read
3. Proofread before you post
4. Keep a nice and friendly tone. No profanity or off color remarks.
5. Never ignore users interacting with you (except trolls and spammers).
6. Keep a professional image
7. Promote your business subtly
8. Be creative and innovative
9. Make the first step to make new contacts.
10. Thank new followers promptly.
11. Keep up to date with the new terminology and customs
12. Study what other business professionals are doing on Twitter.