Mac OS X keyboard shortcut to switch between windows [duplicate]

Mac OS X keyboard shortcut to switch between windows [duplicate]

In Mac OS X, is it possible to switch between windows using a keyboard shortcut? More specifically I want to switch between windows within the same application. An example is I have multiple Firefox windows open. I want a keyboard shortcut to switch between the Firefox windows (or any other application's window). I'm aware of Command-Tab but it only switches between applications (and not windows).