App Lock is a security feature that allows users to apply a lock on almost any type of file or app on their devices, preventing access to locked apps and private data without a password. App Lock can be used to lock individual apps, photos, videos, and contacts. It works by creating a specific PIN or pattern lock that can be used to lock down whatever applications you wish to secure. App Lock is available for both Android and iOS devices and can be downloaded for free from the app store. Some versions of App Lock also offer additional features such as auto-lock based on time or Wi-Fi, disguise feature, and fingerprint or face ID lock. App Lock is a useful tool for protecting sensitive information and ensuring privacy on mobile devices.