Theme Extensions enable the creation of custom theme parameters, enabling you to use your own custom colors, strings, text styles and more, all from within Theme.of(context)! They're great for a white label app, as they allow you to have just one, easy to update file with all of the custom colors and strings for any given client. Just update the file for any given client and compile! You can also make as many as you want, and transition smoothly between then when a user changes themes in your settings.