App pinning is a feature on Android devices that allows users to restrict access to their phone while sharing the screen with others. It can be found in the Settings app under Security > Advanced > App Pinning. Once enabled, users can pin an app's screen, preventing others from accessing other applications unless they enter the user's passcode. To pin an app, swipe up from the bottom of the screen and hold, then tap the app's icon and select Pin. Unpinning can be done through various navigation methods depending on the device's settings. Additionally, Android offers Guest Mode, which creates a separate profile for temporary users, allowing them to use the device without accessing the owner's private information.