Are you a Twitter top dog or a tenderfoot? Unless you're emerging from a six-year cultural hiatus, you are no doubt familiar with the ubiquitous hashtag symbol (#). But if you're wondering how a hashtag is used in the world of tweets and retweets (what is a retweet anyway?), then it's time to brush up on your Twitter terms.

• Direct message (DM)—a private tweet that only the sender and recipient can view; begins with "d username" to indicate for whom the message is intended.

• Favorite—a tweet that a user has bookmarked by clicking the star next to it; these messages are stored within the user's Favorites tab.

• Handle—a Twitter username and the account's accompanying URL, which is captured as www.twitter.com/username.

• Hashtag—a word prefaced by the # symbol, marking keywords or topics in a tweet; this tool was created organically by Twitter users.

• Reply—a tweet posted in reply to another user's message, usually by clicking the "reply" button next to the particular tweet in a user's timeline; replies always begin with "@username."

• Retweet—(noun) another user's tweet that a follower forwards, often to spread news or share valuable findings; (verb) the act of forwarding another user's tweet.

• Trending topic—a keyword or hashtag algorithmically determined to be one of the most popular on Twitter at that moment.

These terms were excerpted from the Twitter Glossary in the January 2012 Infoline, "Twitter for Trainers."