At a glance: Twitter terms you must know

What's in a tweet? To start, 140 characters, including spaces. Then there are the acronyms, symbols and Twitter-specific lingo that could look like alphabet soup to the uninitiated.

Twitter Inc starts trading publicly on Thursday, so you might be wondering what the service is about. Here's a glossary of some of the most common Twitter terms you might encounter, defined in 140 characters or less -

- Tweet: That 140-character message sent out on Twitter. Also, the sound a small bird makes.

- Follow: Find an account you like? Click "follow" to have their tweets show up in your feed.

- RT: Stands for retweet, or resubmitting someone else's tweet to your followers.

- HT: Hat Tip, means you are sharing a link or idea someone else shared first, so you're giving them credit. Not quite a retweet.

- DM: Direct Message, a private message sent to another user. You can send it only to people who follow you.

- @(at): Add before someone's name to reply to them publicly. It's only shown in the feeds of those who follow both of you.

- Egg: Unless you upload a profile photo, an egg will show up in its place. Often a sign of a spam account, or someone new to Twitter.

- #(hash): Hashtags are a way to make posts searchable by topic. Just insert in front of a word, but these days (hash)-less words are indexed, too.

- FF: Follow Friday, Twitter tradition where users recommend other accounts that people should follow. Happens on Friday.

- Trends: Popular topics people are talking about on Twitter at any given time, but not the most popular ever. Can change based on location.

- Promoted tweet, account or trend: Advertisements. Distinguished by an orange arrow and the word "Promoted" next to a tweet, trend or topic.