This article has very insightful thoughts on why certain elements in programs and website are displayed and positioned in certain ways, and introduces you to Fitts’ Law. For example, why is the Start Menu on Windows systems positioned at the bottom left corner? That’s because its one of the easiest places to reach. Your mouse will never go out of screen if you move it to the edge, so you’ll not have to worry about precision. Navigating to the Menu is thus near-effortless. Why are Menu Bars at the top? That’s another edge, although you still have to be precise when navigating sideways, from the File option to the Edit option, but vertically, your mouse will never exceed the top of the screen.
Why are certain buttons positioned far from the rest of the interface? Why are certain buttons positioned at the bottom on the when viewed on the iPhone? How will it affect the users if these buttons are placed at the top instead?
This article addresses such concerns, and will help you see design in a different perspective.