Can you explain Twitter to me?

[Sup?]

I don't understand all the # signs and all that jazz lol.

[Joanna N]

@username - send a reply to another user

#topic when you hash something it contributes to the "trending topics" on the right toolbar. so if someone clicks on one of the topics i.e. Obama - and you've hashed Obama - you'll show up in the search and ppl can click on you

D username - sending a private msg to another user

RT - i.e. RT @username i love you | this is when you retweet (copy and paste) what someone else has said