Hypothetically, if I asked a girl out, and she says yes. It just so happens, that we live close by, and end up having relations that are primarily physical. There's no drama, and sure we talk occasionally, but it's not super deep or something. But we aren't really going after other people.

What exactly would that be classified as? And in general this just got me thinking, what the difference would be between a serious relationship and hooking up.