What is Windows 10 S mode?

Windows 10 in S mode is a version of Windows 10 that's streamlined for security and performance, while providing a familiar Windows experience. Many of the PCs come with version of Windows 10 in S mode preinstalled.

Windows 10 in S mode works exclusively with apps from the Microsoft Store within Windows and accessories that are compatible with Windows 10 in S mode. That means you can install apps only from Windows Store and won't be able to install apps or software from other sources. To increase security, it allows only apps from the Microsoft Store, and requires Microsoft Edge for safe browsing.

You can't even run command line commands. So in a way it''ll protect your PC by running only verified apps from the Store. What actually is Windows 10 in S mode? Let us check some of the FAQs regarding the same.

• How do I get Windows 10 in S mode?
  To get Windows 10 in S mode, you need the right volume license agreement and qualifying devices that are already enabled in S mode. Or you can work with the manufacturer or partner to get it installed when you buy a new device.
• How did Windows 10 S change with the release of the April 2018 Update for Windows 10?
  With the April 2018 Update, Windows 10 S became a mode of Windows 10 (called “S mode”). It's now available in Windows 10 Home edition, Windows 10 Pro, and Windows 10 Pro Education—and you can buy new PCs with an edition of the S mode preinstalled. If you have an existing Windows 10 S device and you install the April 2018 Update or later, you'll have a Windows 10 Pro device in S mode.
• What kind of processor does Windows 10 in S mode run on?
  Windows 10 in S mode can come installed on a PC that has an Intel, AMD, or Qualcomm Snapdragon processor.
• What apps can I use on a PC that's running Windows 10 in S mode?
  You can download and install apps from the Microsoft Store in Windows.
• Can I set Google Chrome or Firefox as my default web browser when I'm using Windows 10 in S mode?
  No. When you're using Windows 10 in S mode, Microsoft Edge is always the default web browser, and Bing is the default search engine. But you can access other browsers and search engines while in S mode. You can download any browser available in the Microsoft Store in Windows, and you can navigate to any other search engine website.If you want to download a browser (or any other application) that's not in the Microsoft Store, you'll need to permanently switch out of S mode. 
• How do I switch out of S mode?
  To increase security and performance, Windows 10 in S mode runs only apps from the Microsoft Store. If you want to install an app that isn't available in the Microsoft Store, you'll need to permanently switch out of S mode.Switching out of S mode is one-way. If you make the switch, you won't be able to go back to Windows 10 in S mode.There's no charge to switch out of S mode, but you won't be able to turn it back on. If you're blocked from switching and your device belongs to an organization, check with your administrator. Your organization can choose to keep all devices in S mode.
  
  On your PC running Windows 10 in S mode, open Settings  > Update & Security  > Activation.
  
  Find the Switch to Windows 10 Home or Switch to Windows 10 Pro section, then select the Go to the Store link.
  
  
  Note: Don't select the link under Upgrade your edition of Windows. That's a different process that will keep you in S mode.
  
  On the page that appears in the Microsoft Store (Switch out of S mode or a similar page), select the Get button. After you confirm this action, you'll be able to install apps from outside the Microsoft Store.
  
  
  
• How do I switch back to S mode?
  Switching out of S mode is one-way. If you switch out of S mode, you'll need to keep using the standard version of Windows 10.

As per this Switching out of S mode will not affect the warranty of your device. Still one can check with their device manufacturer before switching out of S mode. For more details about S mode on various processors, specially  Qualcomm Snapdragon processor, please check this source.