In earlier versions of iOS, the system would notify users of available App Store updates with a badge on the icon (seen above).
You had to open up the App Store, press the Update button, then press Update All. It was rather annoying to keep up with all the apps that needed updating. Sometimes by the time you finished updating, more apps would need updating.
Now with iOS 7, the apps will now automatically update. To make sure that the apps are set to automatically update, go into Settings and scroll until you see iTunes and App Store.
Tap on iTunes & App Store. Then scroll all the way down towards the bottom until see Automatic Downloads.
To turn on automatic app updates, tap in the white oval next to Updates. The apps will now update automatically. Apple even asks you how often you want the apps to automatically update, whether to occur only when you’re on Wi-fi or if it can occur when you’re on a Cellular network. This is great because not everyone might have a data plan that can support automatically updating the apps on a Cellular connection.
If you have automatic app updates turned on, and happen to be curious as to which apps updated, you have two places to find the same information. If you go to the App Store and press on Updates, it will show you when apps last updated. Also, Notification Center can even show you (in the “All” tab) which apps were automatically updated.