Linux is one of the most stable platforms available. That doesn’t mean every application that runs on the system will enjoy the same incredible stability. Truth is, apps crash. It’s almost an inevitability that you’re going to experience a rogue application now and then. When it happens, you need to know how to close the app to get rid of any negative impact the wayward app might have. If it happens rarely, you’re good to force close the app and move on. If, however, you find it happening frequently, you need to have the tools available to help you figure out why this is occurring.