An operating system (OS) is basically a collection of software that manages computer hardware resources and provides common services for computer programs. Operating system is a crucial component of the system software in a computer system.
We can probably see that the term operating system covers many roles and functions. That is the case, at least in part, because of the myriad designs and uses of computers. Nowadays, Computers are present within toasters, cars, ships, spacecraft, homes, and businesses. They are the foundation for game machines, music players, cable TV tuners, and industrial control systems. Since computers have a relatively short history, they have evolved rapidly. Computing started as associate experiment to work out what can be done and quickly enraptured to fixed-purpose systems for military uses, like code breaking and flight plotting, and governmental uses, such as census calculation. The early computers which evolved into general-purpose, multifunction mainframes, and that’s when operating systems were born. In 60s, Moore’s Law foreseen that the number of transistors on an integrated circuit would double every eighteen months, and that prediction has held true. Computers gained in functionality and shrunk in size, which leading to a vast number of uses and a vast number and variety of operating systems. Normally, we have no completely adequate definition of an operating system. Operating systems exist as they offer a reasonable way to solve the problem of creating a usable computing system. The basic goal of computer systems is to execute user programs and to make solving user problems easier. Computer hardware is built toward this goal. As bare hardware alone is not particularly easy to use, application programs are developed. These programs need certain common operations, such as those controlling the I/O devices. The common functions of controlling and allocating resources are then brought together into one piece of software: the operating system. Additionally, we have no universally accepted definition of what is part of the operating system. A simple viewpoint is that it includes everything a vendor ships when we order “the operating system.” The features included, however, vary greatly across systems. Some of the systems take up less than a megabyte of space and lack even a full-screen editor, whereas others require gigabytes of space and are based entirely on graphical windowing systems. A lot of common definition, and the one that we usually follow, is that the operating system is the one program running at all times on the computer—usually called the kernel. In the year 1998, the United States Department of Justice filed suit against Microsoft, in essence claiming that Microsoft included too much functionality in its operating systems and thus prevented application vendors from competing. (For an example, a Web browser was an integral part of the operating systems.) As a result, Microsoft was found guilty of using its operating-system monopoly to limit competition. Today, however, if we look at operating systems for mobile devices, we see that once again the number of features constituting the operating system is increasing. Not only a core kernel is included in mobile operating systems but also middleware—a set of software frameworks that provide additional services to application developers. For example, each of the two most prominent mobile operating systems—Apple’s iOS and Google’s Android—features a core kernel along with middleware that supports databases, multimedia, and graphics.