Windows 11 in S mode is a version of Windows 11 that is designed for security and performance, while providing a familiar Windows experience. It is only available in the Windows 11 Home edition and is designed to run exclusively on apps from the Microsoft Store. This mode is much more energy-efficient than standard Windows, as it runs fewer background processes and services, which can burn energy. Some of the benefits of using Windows 11 in S mode include improved security, optimized performance, and an optimized app store experience. However, it also has some downsides, such as limited software options and features that some people consider essential. If you want to install an app that isnt available in the Microsoft Store, youll need to switch out of S mode. Switching out of S mode is one-way, and you wont be able to go back to Windows 11 in S mode. To switch out of S mode, you can go to Settings > System > Activation and select "Go to the Store" under the "Switch to Windows 11 Pro" section.