Mac OS versions

Major versions of Mac OS and their release dates:

1. Mac OS X 10.0 (Cheetah) - March 24, 2001

2. Mac OS X 10.1 (Puma) - September 25, 2001

3. Mac OS X 10.2 (Jaguar) - August 24, 2002

4. Mac OS X 10.3 (Panther) - October 24, 2003

5. Mac OS X 10.4 (Tiger) - April 29, 2005

6. Mac OS X 10.5 (Leopard) - October 26, 2007

7. Mac OS X 10.6 (Snow Leopard) - August 28, 2009

8. OS X 10.7 (Lion) - July 20, 2011

9. OS X 10.8 (Mountain Lion) - July 25, 2012

10. OS X 10.9 (Mavericks) - October 22, 2013

11. OS X 10.10 (Yosemite) - October 16, 2014

12. OS X 10.11 (El Capitan) - September 30, 2015

13. macOS 10.12 (Sierra) - September 20, 2016

14. macOS 10.13 (High Sierra) - September 25, 2017

15. macOS 10.14 (Mojave) - September 24, 2018

16. macOS 10.15 (Catalina) - October 7, 2019

17. macOS 11.0 (Big Sur) - November 12, 2020

18. macOS 12.0 (Monterey) - October 25, 2021

The naming convention of the operating system changed from "Mac OS X" to "OS X" with the release of version 10.7, and then changed to "macOS" with the release of version 10.12.