Windows 8.1

Windows 8.1 is an operating system by Microsoft. It is a free upgrade for existing Windows 8 users. It replaced Windows 8 and was succeeded by Windows 10 in late July 2015.

This is the last version of Windows that supports processors without SSE3.

RTM

 * The Start button was brought back (although it still leads to the Metro start screen).
 * Computer is renamed to This PC.
 * Clicking the File Explorer icon in the taskbar takes you to This PC instead of Libraries, unlike in Windows 7 and 8. Additionally, Libraries is disabled by default, you can re-enable it by right-click on the navigation pane and choose "Show libraries" or "Show all folders".
 * User folders (Desktop, Documents, Downloads, Music, Pictures, Videos) added to This PC.
 * New customization options for the Start screen.
 * Redesigned PC Settings.
 * The price of the Windows 8 and 8.1 Media Center Pack changed to US$9.99 until it was discontinued on 30 October 2015.

Update 1 (on non-touch devices)

 * When you hover over the top of a Metro app, Windows shows a title bar with minimize and close buttons.
 * Right-clicking on the Start screen opens up a menu instead of the touch-oriented controls at the bottom.
 * You can pin Metro apps to the taskbar.
 * A power button has been added next to the search button on the start screen.