The computer's master control program. When a computer is turned on, a small "boot program" loads the operating system. Although additional system modules may be loaded as needed, the main part, known ...

A legacy platform, also called a legacy operating system, is an operating system (OS) no longer in widespread use, or that has been supplanted by an updated version of earlier technology. Many ...

What is a guest OS (guest operating system)? A guest operating system is the operating system installed on either a virtual machine (VM) or partitioned disk. It is usually different from the host ...

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.