[pavlov]

In the spirit of pedantry, I’ll point out it’s actually called macOS these days.

The ‘X’ and capitalization went away when they finally bumped the version number to 11.

[agsnu]

Actually, it was changed to macOS in 2016 for 10.12 Sierra, to align the branding across Apple's various platforms (iOS/macOS/tvOS/watchOS).