macOS uses a system called defaults to store user preferences and other settings for applications and system services. These preferences include things like font choices or window positions that persist even when the application is closed. While many settings are accessible through the standard Preferences panels, some remain hidden and can be accessed or modified using the defaults command line interface.
Defaults settings are organized into domains, usually corresponding to individual applications or system components. There is also a shared domain called NSGlobalDomain that applies settings globally if not specified elsewhere. Each domain contains keys and values stored as XML property lists, representing various preferences.
The defaults command allows users to interact with these settings directly. Basic commands include displaying help information, listing all domains, searching for specific keys, reading the data type of a key, and renaming keys within a domain.
Examples of defaults commands cover a wide range of macOS features such as the Dock, Screenshots, Safari, Finder, Desktop, Menu Bar, input devices like Mouse and Trackpad, Keyboard, Mission Control, and various system utilities including Activity Monitor and Time Machine.
Users interested in contributing new commands or expanding the list can do so via GitHub by opening issues or submitting pull requests. The website hosting this information was built using VitePress, a modern static site generator.