Stopping Background App Refresh from fetching new content in the background when an iPhone or iPad is connected to your carrier’s cellular network is one way to ensure you stay within your monthly data allotment.
Introduced in iOS 7, Background App Refresh lets suspended apps (those that you quit or run in the background) check for new data so that they always present you with up-to-date content.
As useful as Background App Refresh is, it strains your battery due to periodical data fetching, which sometimes occurs even when your device is locked.
You can enable or disable this feature on a per-app basis in Settings → General → Background App Refresh. You can also save yourself a few taps by quickly disabling Background App Refresh for a single app without launching Settings, and here’s how.