A system software component that is external to the operating system kernel. If the phrase is used to refer to the operating system itself, it is redundant because an operating system "is" software.

An operating system is the essential software that's needed to run your computer's suite of software. Everything from video ...

Just about every piece of technology has some form of an operating system – desktops, laptops, mobile phones, and servers, to name just a few. The Merriam-Webster definition of an operating system?

Operating systems (OS) are the intermediary between computer hardware and software, an essential piece of any digital device. Much like an orchestra conductor, they ensure harmonious communication ...

Software used to control the computer and develop and run applications. It includes programs such as operating systems, database managers, compilers, Web servers, router operating systems and control ...