One of the biggest things that annoys users about Windows 8 is its all-or-nothing Start screen. Windows 10 tries to fix that problem with a separate full-screen tablet mode that it hopes will soothe angry desktop users.
Tablet mode is a new feature that should automatically activate (if you want it to) when you detach a tablet from its base or dock. The Start menu then goes full screen as do Windows Store apps and Settings.
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