Windows 8.1

Windows 8.1 (codenamed Blue) is a free update for the Microsoft Windows 8 operating system.

Despite the fact that Windows 8.1 is a service pack for Windows 8, but unlike Windows NT 4.0/2000/XP/Vista/7 service packs, due to having a different name and change on features, people considered Windows 8.1 as a new version.

Tami Reller, corporate vice president and chief financial officer of the Microsoft Windows division, announced the release of the Windows 8.1 Preview during the Build Windows conference in June, 2013.

Enhancements have been made to the overall Windows 8 experience, including the reinstatement of the Start button, the return of unified search results, new Start screen customization options, and horizontal application snapping improvements with support for up to 4 apps snapped depending on screen resolution. The minimum resolution for snapping has been reduced to 1024X768.

Windows 8.1 also includes new Alarm, Calculator, Movie Moments, and Sound Recorder applications. Internet Explorer 11 was also released with this update. An update of Windows 8.1, known as Windows 8.1 Update 1, was released on 8th April 2014. It allows Store apps to be pinned and includes other updates as well. It also reduces the minimum system requirements for Windows, so that it can be installed on computers having only 1GB of RAM and 16GB of storage.

RTM
Windows 8.1 was not that much of an revolutionary change as Windows 8 was from Windows 7, rather it mostly focused on improvements, which however are significant.
 * 1) The Start screen can now show the Windows desktop as its background.
 * 2) The possible sizes for app icons on the Start Screen was increased, with smaller and bigger options.
 * 3) Snap from Windows 8 has been improved, now allowing up to 4 apps to be snapped depending on resolution, and reducing the minimum resolution required for snapping to 1024x768.
 * 4) Camera can now be launched from the lock screen by swipping up.
 * 5) New apps such as Health and Fitness were introduced, and existing apps were greatly improved. Store was also redesigned.
 * 6) The PC Settings app was redesigned, and now includes far more options.
 * 7) Unified search, present in Windows 7 but removed in Windows 8, was bought back.
 * 8) The Start button was bought back.
 * 9) The option to show the desktop instead of the Start screen was introduced.
 * 10) OneDrive was greatly improved, and included the ability to set files as 'placeholders'.
 * 11) New wallpapers were added.
 * 12) Full camera backup support to OneDrive was added.

Update 1

 * 1) Metro apps can now be pinned to the taskbar.
 * 2) Metro apps have a desktop-like title bar that shows whenever the mouse is moved to the top part of the app.
 * 3) Search and Power(only for >8 inches displays) icons are now shown on the start screen.
 * 4) The taskbar can be invoked in the Start Menu and metro apps by moving the mouse to the bottom of the display.
 * 5) PC Settings now shows a option to use the legacy Control Panel, and it also adds some new options such as the ability to view disk space.
 * 6) Optimizations were done for reducing the disk space to 16 GB HDD and reducing the RAM to 1 GB. A new mode called as WIMBoot was introduced for such devices, which are intended to be low-cost tablets.
 * 7) A new edition called Windows 8.1 with Bing was introduced, free to tablets having displays <10 inches. This version is essentially identical to Windows 8.1 with some minor restrictions for manufacturers.

Removed or degraded features

 * 1) The introductory guide about the Start menu at the post-OOBE stage was removed.
 * 2) Windows Easy Transfer included in Windows 8.1 no longer includes the option to transfer files and settings to another device, only vice-versa.

Milestone 1

 * 6.2.9299.0.fbl_partner_out06.130117-1707 - Leaked on March 30th, 2019
 * 6.3.9319.0.winmain.130208-1820
 * 6.3.9347.0.winmain_bluem1.130220-1504
 * 6.3.9354.0.fbl_partner_out11.130301-2000
 * 6.3.9364.0.fbl_partner_out13.130315-2105 - Leaked on March 24th, 2013
 * 6.3.9369.0.fbl_partner_out14.130324-1300 - Leaked on April 16th, 2013
 * 6.3.9370.0.fbl_loc.130325-2000

Milestone 2

 * 6.3.9374.0.fbl_partner_out15.130329-2355 - Firstly partially leaked, then fully leaked on April 19th, 2013.
 * 6.3.9379.0.fbl_partner_out16.130410-0711
 * 6.3.9385.fbl_partner_out17.130415-2049 - Leaked on May 1st, 2013

Pre-Milestone Preview

 * 6.3.9403.0.fbl_srv2_partners.130509-2000
 * 6.3.9405.0.fbl_partner_out20.130510-2330
 * 6.3.9410.0.fbl_partner_out21.130522-1653
 * 6.3.9415.0.fbl_partner_out22.130525-0845 - Leaked on February 4th, 2020

Milestone Preview

 * 6.3.9418.0.winmain.130530-1905
 * 6.3.9419.0.fbl_partner_out23.130603-1634 - Leaked on May 5th, 2020
 * 6.3.9431.0.winmain_bluemp.130615-1214 - Official Preview

Pre-RTM

 * 6.3.9448.fbl_partner_out25.130621-2030
 * 6.3.9457.fbl_loc.130708-1930
 * 6.3.9460.fbl_partner_out28.130712-1918
 * 6.3.9465.fbl_partner_out29.130719-2136
 * 6.3.9466.0.fbl_loc.130722-1930
 * 6.3.9471.0.fbl_partner_out30.130726-2004
 * 6.3.9477.0.fbl_partner_out31.130803-0736
 * 6.3.9483.0.winblue_rtm.130809-2020

RTM

 * 6.3.9600.16384.winblue_rtm.130821-1623

Post-RTM

 * 6.3.9600.fbl_uex_drx.130826-1600

General Availability Update

 * 6.3.9600.16422.winblue_gdr.131006-1505

Spring 2014 Update

 * 6.3.9600.17031.winblue_gdr.140221-1952