Newbie Law: What is a Pleading?

OK, to start off with, I remember during the beginning days of Civ Pro, wracking my brain trying to figure out, What is a pleading? What's the difference between this specially-treated, mythical "pleading" and a paper, or a motion, or a subpoena?

And I asked my friends, and they all kind of shrugged, as if it wasn't important--and it's not, if all you do is memorize what the professor spits out at you--or they'd suggest that maybe it's something that you file? Well, don't you file "papers?"

These are the kinds of things that people assume that law students should know or that they can easily find out. And I'm sure that there are lawyers (and professors) out there who aren't exactly sure what constitutes a pleading and what doesn't.

And, now, thinking and ranting about this, I'm not sure if *I* know exactly what it is. If I had to define it, I'd say that a pleading is (drumroll)... The complaint or the answer. These two documents set out what each side is "pleaing" of the court.

Everything else is either a motion (but only if it's called a motion) or a paper or some other "document."

I'd also think that "filings" are papers that you file, so a subpoena, which wouldn't necessarily be filed with the court, would *not* be a filing. (And, on a side note, a subpoena, though it collects "evidence" (colloquially) is not "discovery"--but it feels like it, doesn't it?)