iOS is generally smart enough to keep a background app from needlessly eating up battery life or system resources. But sometimes, stuff goes wrong. An app may glitch out and stop responding, or it may eat up absurd amounts of data in the background. If that happens, closing a troublesome app is as easy as flicking it away.
To start, open up the app switcher by double-pressing the Home button (note that you’re actually pressing the button down here—you aren’t just tapping the Touch ID sensor). You’ll get a series of icons and app thumbnails you can swipe through. If you want to switch to another app, simply tap on the app’s icon or thumbnail.
To close an app, though, simply swipe upward on that app’s thumbnail until you flick it off of the screen. You can close just one app, or close them all if you like. Once you’re done, either tap on an open app or press the Home button.
Under normal circumstances, you shouldn’t have to quit an app unless it’s causing problems. Still, you might want to clean out the app switcher every now and then, because it can be a pain to swipe though 30 apps.
If an app still gobbles up too much data or battery power on a consistent basis while in the background, you might want to turn off background app refresh for that app. Open the Settings app, tap General, then tap Background App Refresh. Find the troublesome app, the slide the toggle next to its name to the “off” position.