When you install an app on Android, you're asked to agree to a host or permissions which the software requires—but there's no option to tweak them. Now, Android Police has discovered a new feature in Android 4.3 which lets you do just that.
Called Apps Ops, the feature is baked into Android 4.3—though it's also currently hidden by default. Still, a new third-party app called Permissions Manager brings it to life, allowing to fine-tune what other apps on your phone get access to. So, you can selectively choose for apps to read your contacts, access location, whatever. Or not, as the case may be. You can download the app here.
It's not clear if Google has any intention of officially activating the feature, but in the meantime it's an incredibly handy feature, even it does require a third-party app. It goes without saying that you need Android 4.3 to use it, though. [Android Police via Engadget]