Intonation in "What's up?"
As I know the question "What's up?" can be used as a greeting or a question. Is there any difference in its intonation in these two cases? How to understand whether you should say "Hi" in response to it or start describing what is going on in your life or in the place where you are :)?
“What’s up?” is a greeting whose meaning is mostly irrelevant in that the asker doesn’t want an answer to the literal question which means something like “What is new?” or “What’s happening (right now/in your life)?”. The simplest response if you don’t have information you want to share immediately with the asker is probably just to say something like “not much”, “not too much”, or “hey (man/dude)”. If you’re offered “what’s up” in response to a greeting of your own, you should read it as a request for you to proceed to the content part of what you want to talk about. Source: http://english.stackexchange.com/questions/2471/what-is-an-appropriate-response-to-whats-up-greeting