MacOS

macOS is a UNIX-based operating system that was developed by Apple. The "classic" Mac OS was introduced in 1984 alongside the first Macintosh and remained in primary use on Mac PCs until the introduction of Mac OS X in 2001.

The first ever officially released version of Mac OS, System 1, was released on January 24, 1984. It was renamed from System to Mac OS in version 7.6, which was released in 1997. Mac OS X was released in 2007.

All versions of Mac OS before macOS 10.12 "Sierra" (2016) are to be retroactively referred to as either "Mac OS X", "Classic Mac OS", or "OS X."

macOS is created in 2001. It was developed in earlier than 1999, and back in March 16, 1999 Apple releases Mac OS X Server 1.0, which was the first way to Mac OS X era. Then they releases public beta in September 13, 2000, revealing Dock, menu bar, new interface. Tiger is the first release to adopt Intel processors and x86 archeticture in general. Mac OS X is released in March 24, 2001 as a version 10.0, then renamed to OS X in version 10.8, then to macOS in 10.12. While Microsoft, and majority of OS creators hides their codenames, Apple publics their codenames in macOS, naming a new codename every version, while they calling macOS versions 10.0-10.8 after big cats, since 10.9 they naming after major California landmarks. Last versions of macOS is released in early October, with macOS 10.15 released in October 7, 2019.

In June 22, 2020, macOS Big Sur (version 11) was revealed at the WWDC 2020. Prior to the announcement, it was supposedly released to developers. Big Sur is notable for being the first macOS version to support Apple M chips, Apple-designed processors marketed as Apple Silicon, and ARM-based CPUs.

Version History
Legend: Old version   Latest version   Latest preview version   Future release