A mode in Windows 10 that runs apps downloaded and installed only from the Microsoft Store. Microsoft has not divulged the meaning of "S," but "Secure" has been suggested because users cannot install apps from a CD/DVD, USB drive or their network. Like all Windows 10 versions, OneDrive cloud storage is included. Edge is the default Web browser, and schools can provision machines from a USB drive.
Windows 10 in S Mode
Windows 10 S was introduced in 2017; however, the April 2018 update officially changed the name from "Windows 10 S" to "Windows 10 in S mode."
Switch Out But Not Back
In order to run an app that did not come from the Microsoft Store, Windows can be taken out of S mode and switched to Windows 10 Home or Pro. However, users cannot revert to S mode later on.
A Chromebook Competitor
Introduced on Microsoft's Surface Laptop, Windows 10 S was designed to compete with Chromebooks, which have similar functionality. As of 2019, companies such as HP, Dell, Asus and Acer have debuted Windows 10 S laptops. See Surface Laptop