Windows 8 has made switching between apps easier but closing them is not intuitive. I found myself puzzled at first at what to do when I was done with an app. But, moving the mouse to the top left corner will display the previous app used. Moving it down the left side displays all the running apps. Left clicking any one of them switches Windows to that app. Right clicking brings up a menu where you can close the app. Otherwise, there’s no instinctive way to close an app.