https://arstechnica.com/gadgets/2020/11/macos-11-0-big-sur-the-ars-technica-review/

The era of Mac OS X is over. Kind of.

For the first time in almost two decades, Apple has decided to bump up the version number of the Mac’s operating system. The change is meant to call attention to both the pending Apple Silicon transition—Big Sur will be the first macOS version to run on Apple’s own chips, even if it’s not the first to require those chips—and to an iPad-flavored redesign that significantly overhauls the look, feel, and sound of the operating system for the first time in a long while. Even the post-iOS-7 Yosemite update took pains to keep most things in the same place as it changed their look.