I'm inexperienced, but I've been reading about the mashing/lautering process lately. It's a fairly simple process that for some reason gets overcomplicated when an explanation is attempted. I think I understand it, so here goes:
Sparging is the process of rinsing to extract fermentable sugars from the grain. As I understand it, it involves pouring the wort back into the mashtun after draining/"lautering" the initial mash. Think of it as a second rinse for the grains.
There's fly sparging, where you spray the wort in and drain it at the same time/rate. Fly sparging is generally considered the most efficient, meaning more fermentable sugars are extracted from the grains. Batch sparging is where you pour it all in at once, and then drain. It is a much simpler method, but considered less efficient and thus may require more grain to get the right starting gravity. Most homebrewers get acceptable results using this method.
jb