Operating Systems

The (OS) also known as the operating system, is a software, consisting of programs and data, which runs on computers, manages computer hardware resources, and provides common services for execution of various application software.

For the process of  hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between application programs and the computer hardware, although the application code is usually executed directly by the hardware and will frequently call the OS or be interrupted by it. Operating system is found on almost any device that contains a computer—from cellular phones and video game consoles to supercomputers and web servers.

Examples of the most popular modern operating systems for personal computers are: Mac OS X, Microsoft Windows, GNU/Linux, and Unix

Summary

An OS consists of many parts. Most important components is the kernel, which controls low-level processes that the average user usually cannot see: it controls how memory is read and written, the order in which processes are executed, how information is received and sent by devices like the monitor, keyboard and mouse, and decides how to interpret information received from networks. The component that interacts with the computer user directly, allowing them to control and use programs is known as the user interface. It is graphical with icons and a desktop, or textual, with a command line. The user interfaces provide services and code libraries that let applications developers write modular code reusing well defined programming sequences in user space libraries or in the operating system itself. Which features is considered part of the operating system is defined differently in various operating systems. Let us consider an example, Microsoft Windows considers its user interface to be part of the operating system, while many versions of Linux do not.