Deeper is a customization application for macOS that enables hidden features of the operating system and Apple applications. It allows you to modify internal settings of the Finder, Dock, Safari, iTunes, QuickTime, the login window, and Spotlight, among other components, through a graphical interface. The program operates by modifying system preferences (plist) that are not available in the standard macOS configuration panels. It is designed for users who require detailed control over the behavior and appearance of their system.