How do you enable facebook to stop letting people talk to you on a chat pop-up?

Question From User - Answers in Comments.

I have facebook and all of my friends always want to talk to me when I just want to go on facebook, search people's profiles and stuff without people popping up chats and trying to talk to you. Anyway, I was wondering whether there is a way to stop this from happening? If so that would be a great help!:]