What does 'what's up' or 'what(are) you up to' mean?
I used to use it meaning 'what are you going to do now' but somtimes people tell me 'hi, what are you up to' I don't know what it means or how to reply.
Thank you in advance!
It depends upon who is asking. If a friend or relative asks "what are you up to?" it's just another way of asking "how are you and what have you been doing lately, what's new?" If it's your boss at work and he asks "what are you up to?", he's probably fishing around to find out how busy you are, or to see if he can assign you yet another project.