An operating system that is designed for a server. Normally, it is a complete operating system with file, task and job management; however, with some earlier products ...

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.

Linux is a tried-and-true, open-source operating system released in 1991 for computers, but its use has expanded to underpin systems for cars, phones, web servers and, more recently, networking gear.