VERY useful feature to stop accidentally breaking out of an app. Useful also for people streaming from their phones

Ever needed to hand your phone to a kid? Even if you don’t want to, sometimes you’re trying to keep them quiet at a restaurant, or calm them down at the doctor’s. But handing over an unlocked phone is just asking for the kid to delete all your home screen shortcuts (or, worse, work emails). Fortunately there’s a way to fix this.

Source: Your Android Phone Has a Built-In Childproofing Feature