Operating System is a program that acts as an intermediary between a user of a computer and the computer hardware. It controls and coordinates use of hardware among various applications and users.OS is a resource allocator that manages all resources and decides between conflicting requests for efficient and fair resource use.There are two goals of operating system: one is to execute user programs and make solving user prroblems easier, the other is to make the computer system convenient to use.

There are many example of operating system.

① Unix and Unix-like operating systems

The Unix-like family is a diverse group of operating systems, with several major sub-categories including System V, BSD, and Linux. UNIX-like" is commonly used to refer to the large set of operating systems which resemble the original UNIX. Unix-like systems run on a wide variety of computer architectures. They are used heavily for servers in business, as well as workstations in academic and engineering environments. Free UNIX variants, such as Linux and BSD, are popular in these areas.

②BSD and its descendants

A subgroup of the Unix family is the Berkeley Software Distribution family, which includes FreeBSD, NetBSD, and OpenBSD. These operating systems are most commonly found on webservers, although they can also function as a personal computer OS. The Internet owes much of its existence to BSD, as many of the protocols now commonly used by computers to connect, send and receive data over a network were widely implemented and refined in BSD.The World Wide Web was also first demonstrated on a number of computers running an OS based on BSD called NeXTSTEP.

③macOS

macOS (formerly "Mac OS X" and later "OS X") is a line of open core graphical operating systems developed, marketed, and sold by Apple Inc., the latest of which is pre-loaded on all currently shipping Macintosh computers. macOS is the successor to the original classic Mac OS, which had been Apple's primary operating system since 1984.

Features: Multi-platform compatibility mode, prepare for security and service, take up less memory, and multiple development tools.

④Linux

Linux is Unix-like, but was developed without any Unix code, unlike BSD and its variants. Because of its open license model, the Linux kernel code is available for study and modification, which resulted in its use on a wide range of computing machinery from supercomputers to smart-watches. Although estimates suggest that Linux is used on only 1.82% of all "desktop" (or laptop) PCs, it has been widely adopted for use in servers and embedded systems such as cell phones. Linux has superseded Unix on many platforms and is used on most supercomputers including the top 207.

⑤Google chrome OS

Chrome OS is an operating system based on the Linux kernel and designed by Google. It is developed out in the open in the Chromium OS open source variant and Google makes a proprietary variant of it (similar to the split for the Chrome and Chromium browser). Since Chromium OS targets computer users who spend most of their time on the Internet, it is mainly a web browser with limited ability to run local applications, though it has a built-in file manager and media player (in later versions, (modified) Android apps have also been supported, since the browser has been made to support them). Instead, it relies on Internet applications (or Web apps) used in the web browser to accomplish tasks such as word processing.Chromium OS differs from Chrome OS in that Chromium is open-source and used primarily by developers whereas Chrome OS is the operating system shipped out in Chromebooks.

⑥Microsoft Windows

Microsoft Windows is a family of proprietary operating systems designed by Microsoft Corporation and primarily targeted to Intel architecture based computers, with an estimated 88.9 percent total usage share on Web connected computers. The latest version is Windows 10. In 2011, Windows 7 overtook Windows XP as most common version in use. Microsoft Windows was first released in 1985, as an operating environment running on top of MS-DOS, which was the standard operating system shipped on most Intel architecture personal computers at the time. In 1995, Windows 95 was released which only used MS-DOS as a bootstrap. For backwards compatibility, Win9x could run real-mode MS-DOS and 16-bit Windows 3.x drivers. Windows ME, released in 2000, was the last version in the Win9x family.

Later versions have all been based on the Windows NT kernel. Current client versions of Windows run on IA-32, x86-64 and 32-bit ARM microprocessors. In addition Itanium is still supported in older server version Windows Server 2008 R2. In the past, Windows NT supported additional architectures. Server editions of Windows are widely used. In recent years, Microsoft has expended significant capital in an effort to promote the use of Windows as a server operating system. However, Windows' usage on servers is not as widespread as on personal computers as Windows competes against Linux and BSD for server market share.

ReactOS is a Windows-alternative operating system, which is being developed on the principles of Windows – without using any of Microsoft's code.

 

Features:  1. The Windows operating system has excellent man-machine operability.

Windows operating system supports more application software.

The Windows operating system has good hardware support.