All I have read in the electricity class is that AC is any type of current which actually reverses its directions periodically. I have also read all sorts of mathematical expressions concerning sine-wave form of AC. I have also understood how AC generator works. These topics had never bothered me. But now when I think on how is AC really applied to household three pin plugs the story that follows really puzzles me. Well, I somehow understood that hot wire actually serves the purpose of having definite potential [which obviously changes]. The ground, as I have read in school text-books, "buries" the deadly current. But I could not understand as to what does the neutral sitting there do. I wish somebody from PF gives me the answer. Thanks in advance.