Software versioning is the process of assigning either unique version names or unique version numbers to unique states of computer software. Within a given version number category, these numbers are generally assigned in increasing order and correspond to new developments in the software. At a fine-grained level, revision control is used for keeping track of incrementally-different versions of information, whether or not this information is computer software, in order to be able to roll any changes back.

macOS Big Sur is the seventeenth major release of macOS, Apple's operating system for Macintosh computers. It was announced at Apple's Worldwide Developers Conference (WWDC) on June 22, 2020, and was released to the public on November 12, 2020.