From the Apple menu in the top-left in the corner of your screen, choose About This Mac. You’ll see the macOS name, such as macOS Catalina followed by a version number. Need to know the build number, click on the version number.
Version and version number
| macOS Version | Version Number |
|---|---|
| macOS Monterey | 12.5 |
| macOS Big Sur | 11.6.8 |
| macOS Catalina | 10.15.7 |
| macOS Mojave | 10.14.6 |
| macOS High Sierra | 10.13.6 |
| macOS Sierra | 10.12.6 |
| OS X El Capitan | 10.11.6 |
| OS X Yosemite | 10.10.5 |
| OS X Mavericks | 10.9.5 |
| OS X Mountain Lion | 10.8.5 |
| OS X Lion | 10.7.5 |
| Mac OS X Snow Leopard | 10.6.8 |
| Mac OS X Leopard | 10.5.8 |
| Mac OS X Tiger | 10.4.11 |
| Mac OS X Panther | 10.3.9 |
| Mac OS X Jaguar | 10.2.8 |
| Mac OS X Puma | 10.1.5 |
| Mac OS X Cheetah | 10.0.4 |