Guided Access is an accessibility feature in iOS that allows to you to lock an iPhone or iPad to one specific app. As long as Guided Access is enabled, only that one specific app can be used, and there's no way to exit it for the Home screen or any other app. Guided Access can be extremely useful in education settings, to help kids focus for learning math, language, and other skills, and for working with people on the autistic spectrum. Guided Access can even be used to create a "guest mode" so you can hand your device to someone and let them use Safari, iBooks, Video, or a game without having to worry about them snooping through your personal information. All you've got to do it set it up and activate it!