If you've got an iPhone or iPad running iOS 6 or higher, you've got Guided Access. This feature is especially great to use with small children that you don't want to have access to certain apps. Once you've launched them into the app they are allowed to be in, you can take it one step further by disabling touch for certain areas of the screen you may not want them having access to.
Follow along and we'll show you how.
That's all there is to it. Whoever is using the iPhone or iPad will not be able to exit that app or tap on the areas of the screen that you've specified during setup.