1.Microsoft Windows operating system is a set of operating system developed by Microsoft corporation in the United States. It came out in 1985. At first, it was only a Microsoft-DOS simulation environment.

Windows USES a GUI in graphical mode, which is much more user-friendly than the way Dos used to require input instructions. As computer hardware and software continue to upgrade, so does Microsoft's Windows, From the 16-bit, 32-bit and 64-bit architectures, the system versions from the original Windows 1.0 to the enterprise operating systems known as Windows 95, Windows 98, Windows 2000, Windows XP, Windows Vista, Windows 7, Windows 8, Windows 8.1, Windows 10 and Windows Server, Microsoft has been working on the development and improvement of the Windows operating system.

2.Unix was an operating system that emerged in the early 1970s and can be used as a stand-alone operating system as well as a network operating system. Unix has been widely used as a development platform and desktop operating system, and is now mainly used in engineering applications and scientific computing.

3.Linux, known as GNU/Linux, is a freely usable and freely distributed UNIX-like operating system. Its kernel was first released in 1991 by Linus Benadector Torvac. Inspired by Minix and UNIX ideas, it is a POSIX and UniX-based multi-user, multi-tasking, multi-threaded, and multi-CPU operating system. It runs major Unix utility software, applications, and network protocols. It supports 32-bit and 64-bit hardware. Linux is a stable multi-user network operating system, which inherits the design idea of Unix with network as the core. There are hundreds of different distributions of Linux, such as debian based on community development, ArchLinux, and Red Hat Enterprise Linux based on commercial development, SUSE, Oracle Linux, and so on.

4.Mac OS is an operating system that runs on Apple's Macintosh computers. Mac OS was the first commercially successful graphical user interface (GUI) operating system.Mac system is a graphical operating system based on XNU hybrid kernel. An operating system that cannot normally be installed on a regular PC. Developed by Apple itself. The MAC's operating system is now operating on OS 11, the biggest change to the MAC in its 15-year history. The new system is very reliable; Many of its features and services reflect Apple's philosophy.What's more, the computer viruses that wreak havoc almost always target Windows, and the MAC is rarely attacked by viruses because of its different architecture from Windows. The macOS operating system interface is very unique, highlighting the image of ICONS and human-computer dialogue. Apple develops not only its own systems, but also its own hardware.