Control which apps can refresh in the background on your iPhone or iPad.
Background refresh is part of what allows any app for iPhone or iPad to appear to be multitasking all the time. The truth is, they're really multitasking "just in time" by updating in the background whenever they have the opportunity — or right before they figure you'll be launching them.
In spite of how efficient Apple has tried to make background refresh, some apps still manage to consumer a ton of power and resources. Yes, looking at Facebook so hard... Luckily, if either your battery life or your data limit is a concern, you can turn off background refresh all together — or just for those apps you don't consider that important.
Full article can be found at iMore