In .Net there are methods that start with 'On', such as OnPaint, OnResize.

I know I can call thes methods, but I know very little about them. What are they, when do you use them, and what's the correct way to invoike them - meaning how do you create a propert event args class for the method you're calling?

My form automatically calls OnPaint at certain times, and anytime I call Invalidate(), but if I wanted to call it on my one (or would i?), how do you get the correct arguments?