The best description of how Cocoa’s views are designed that I could find from Apple is in the Cocoa Views Guide PDF in the chapter called View Geometry. If you’re trying to get your head around what a CGRect is and why self.view.frame.origin.x++ doesn’t work, that’s required reading. (A hint to the latter: view.frame is return-by-value; CGRect is a struct, self is an object.)

That said, here’s a handy graphic to not only help you get your head around when to use frame and when to use bounds, but also what they mean in the grand scale of things. Also included are some visual guides on when to use some handy CGGeometry.h functions to do some work for you.