Force-quitting an application is a quick way to clear a program that is hanging, running slowly, or otherwise cannot be quit by normal means using the Quit function in the Application menu. While you might be familiar with the standard Force-quit dialogue box to force-quit programs, there are a number of other ways to do this.
First and foremost is, of course, the force-quit window itself, which can be invoked by choosing “Force Quit” from the Apple menu, but can also be invoked by pressing Option-Command-Escape. This hotkey makes the Force-quit window easy to access; however, it also has another function. If you are using a full-screen application such as a game, and the force-quit window does not show, you can hold this hotkey for several seconds, and the foremost application should shut down. This might not work in all cases, but is worth a try before resorting to hard-resetting your Mac.
The force-quit window allows you to kill applications running in your user account.
The second option is the Dock, where either before or after right-clicking an icon to view its contextual menu, you can hold the Option key to change the standard “Quit” command in the menu to “Force Quit.”
Beyond the specific force-quit options, you can use the Activity Monitor utility (in the Applications > Utilities folder) to select most running processes on the system and send them a kill signal by clicking the Quit button in the toolbar. When you do this, Activity Monitor will ask you whether to force-quit or perform a standard quit action on the selected process. Before force-quitting your program, try the standard quit option to see if that works. Sometimes even when a program is hung up and its menus are not responding, you can use this approach to more safely quit the program.