At any given time you can reset your Nexus 4 smartphone to the factory default settings, meaning you will bring your phone back to the same state as it was on a day when you took it out of the box.
Lots of people think using a layer mask is only for the advanced Gimp users, fortunately this isn't the case at all. Let me explain you the basic usage of layer mask on a easy to follow step-by-step example.
If you are a "private" person and don't want your profile picture or name to appear on your friend's feed next to ads you liked, then follow this steps.