Windows has gone through many versions since its initial release in 1985, starting with Windows 1.0 and progressing through Windows 2.0, 3.0, 3.1, NT 3.1, and NT 3.5 before the 5th major release of Windows 95 which featured a new GUI and was codenamed Chicago, alongside Windows NT4.0 which was codenamed Shell Update Release.

1. Windows
The Most Successful OS.

2. Windows 1.0
• First Windows Operating System

3. Windows 2.0
• Second Windows Operating System

4. Windows 3.0
• New GUI
• Third Windows Operating System

5. Windows 3.1/3.11
• Fourth Major Release

6. Windows 3.2
Chinese Language Only
Minor Release

7. Windows NT3.1
First OS to use the NT
Kernel

8. Windows NT 3.5/3.51
• Minor Update To Windows NT 3.1

9. Windows 95
• New GUI Again.
• 5th Major Release
• Codenamed Chicago

10. Windows NT4.0
• Codenamed Shell Update Release (SUR)