Android Lollipop shipped with a nifty security feature that you may not know of! It's called screen pinning, and what it does is to pin an app of your choice to your smartphone or tablet's display. The very simple idea is about pinning an app, handing the device to someone who wants to use it, and letting them use only, and only this one app that's been pinned to the screen. Moreover, the feature can be combined with the typical screen lock (pattern, pin, password, etc), so if one presses the power button and locks the device, they'll have to get through the screen lock before they get to the pinned app.
Genius, huh? The only downside is that it's pretty easy to learn that pressing the triangle and square keys together at the same time gets rid of the pinned app. But still, going online and reading guides isn't that easy for small children or older relatives who want to entertain themselves for a bit with your phone. In such cases, app pinning might work out flawlessly. Here's how to set it up on your Lollipop-running device!
How to secure your Android Lollipop device with screen pinning