To open an app on the Start screen, just tap or click it.
If the app you want isn’t visible on the Start screen, and you have a keyboard, you’ll love how easy it is to open something: At the Start screen, just begin typing its name. You’ve instantly entered the search mode; the screen shows you only the names of matching apps as you type.
If the one you want is first in the results, just press Enter to open it. If not, tap or click its tile, or use the arrow keys to highlight a tile and then press Enter to open it.
TileWorld apps don’t have Close buttons, so you might wonder what you’re supposed to do when you’re finished using one.
Answer: Generally, nothing. Leave it open; it doesn’t slow your machine down or cost you anything. To use a different app, just return to the Start screen and open it. Or use the app switcher described on The Two Task Switchers.
But there are times when you might want to hide, close, or restart an app. Hiding it means that it won’t show up in your app switcher (list of recent apps); restarting it can be helpful when it’s glitching out and you want to start fresh.
In Windows 8.1, Microsoft tripled the flexibility of the “close this app” gesture. Now it can perform any of those three functions: hide, close, restart.