Guest Operating System

What Does Guest Operating System Mean?

A guest operating system (guest OS) is an operating system (OS) that is secondary to the OS originally installed on a computer, which is known as the host operating system. The guest OS is either part of a partitioned system or part of a virtual machine (VM) setup. A guest OS provides an alternative OS for a device.


Techopedia Explains Guest Operating System

In disk partitioning, a guest OS is simply another instance of the same operating system that can boot up for controlling a certain partitioned memory set. A virtual machine (VM) process is much different, in that a guest OS can be a different OS alternative. In VM setups, a guest OS is delivered through a virtual machine environment through a tool called a hypervisor. Again, the machine will typically have a host OS, where the guest OS will operate "within" the host OS. This can lead to limitations on file saving and other operations within the guest OS, depending on whether the guest OS is said to be "persistent."

Part of the emergence of guest operating systems in VM systems has to do with the benefits provided by virtualization. These revolutions in computing coincide with the more general concept of cloud computing, where resources are delivered, rather than hosted, in physical local hardware setups. In addition, a guest OS often takes advantage of a lean OS build, where memory requirements are further alleviated. VM setups can help with licensing issues, system requirements and more, making these an attractive part of an outsourced computing service.


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Margaret Rouse
Technology Expert

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.