There are some terminologies(vocabulary) that are commonly used on Twitter but which some people, especially new tweeters, are not quite familiar with. Understanding these terminologies will make tweeting a more pleasant experience; and they are very easy to learn.
1. Twitter Handle
A Twitter handle is also known as a username. This is the name you select to represent you on Twitter.
2. To Follow
Following someone on Twitter is the action users take to subscribe to someone's updates on Twitter.
3. Follow Back
To follow back is to subscribe to the updates of someone who has recently started following you. In Twitter's notifications settings, you can indicate whether you would like to receive an email alert whenever a new person follows you.
4. Follow
A follower is a person who has subscribed to receive your updates. You can view your total number of followers on your Twitter profile page.
5. Status Update
A status update is also known as a tweet. Each update can be no longer than 140 characters.
6. @Reply
An '@' sign in front of a twitter handle is a public message sent from one twitter user to another by putting @username anywhere within the body of the tweet.
7. Direct Message (DM)
A DM is a private message sent from one Twitter to another either by clicking on the "message" link on their profile or typing D USERNAME.
8. Twitter Stream
A twitter stream is a list of a person's real-time updates and is found on your account page.
9. Hashtag (#)
A hashtag is a twitter tagging system used to aggregate the conversation surrounding an event, topic, or theme.
10. Tweet-up
A tweet-up is an event specifically organized for Twitter users to meet up and network, usually, informally.
11. Retweet (rt)
A Retweet is an action taken to repeat what someone else has already tweeted.
12. Twitter Lists
Twitter lists are public lists that any twitter user can create. Twitter lists generate Twitter streams that include specific Twitter users.
13. Trending Topics
Trending topics are words, phrases, or hashtags that are popular on Twitter at a given time.
14. Promoted Tweets
Promoted Tweets are tweets that have been supported and promoted by paid marketing efforts.