App Ops lets you fine-tune app permissions

Google built an interesting tool into Android 4.3 that we weren't actually supposed to know about: App Ops is an interface that details—and controls—all the permissions used by apps on your phone or tablet.

The permissions awarded to an app could involve anything from granting network access to parsing your contacts list. Most of the time, these permissions are legitimate and enable features you want, but App Ops lets you kill individual permissions on a per-app basis for improved privacy. App Ops can only be accessed on Android devices with a special third-party app like this one from Color Tiger, but the Play Store is packed with other apps that do this.

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Third-party App Opps controllers let you fine-tune app permissions.
Apps are sometimes organized in App Ops by permissions, not name. As such, it can take a little time to find the app you want to fine-tune for permissions. But when you spot your target—Facebook, for example—it's a simple matter to toggle the switches next to the permissions you want to shut off.

App Ops is accessible without rooting your hardware in Android 4.3 through 4.4.1. In newer versions, Google has removed all the UI elements for this feature—but it can still be accessed via rooting, though. Members of the Android team have noted that App Ops is only a development tool and not intended for end users. It does have the potential to break apps, so it's not exactly a "supported" feature. Be careful if you decide to use it.