Some commonly used terms:
Hashtag:
Hashtags are tracked by twitter automatically. They are like tags and helps you to add additional metadata to your tweet and allows you to create groupings on twitter
Example: Have you seen the product #rabbit from #rabbitsoft
the @ sign
The @ sign followed by a username, such as @example, allows users to direct replies to each other.
“RT” or “retweeting” means forwarding an information to your followers. Here is how you do it:
RT @originalsender: original message