Unlike with Windows, the X button on a Mac closes the window but does not quit the app. If you are coming to Mac after a long tenure with Windows, then you might get tripped up when you click the red X in the upper-left corner of a window only to discover that the app is still running after the window closes. Here are ten shortcuts for general Mac use that didn't fit in any of the above apps. I've covered shortcuts for Finder, iTunes, Safari and Spotlight.
