When you are using any application on your iPhone or Touch, you can leave the application and return to the launcher screens of icons with a quick tap of the ‘Home’ hardware button. 

Not a normal situation, but an application can get confused and hang… which results in nothing happening when you tap the screen or tap the Home button. Before you restart the whole system as we mentioned before here, you can just force quit the one application. 

Force quit an application is as simple as…