What is virtualization?

With respect to computing, virtualization is the process of creating a virtual version of something, such as a server or computer system, using software instead of hardware. For example, a large server may be used to store multiple virtual servers or desktop environments. For IT professionals, virtual environments are easier to maintain as they do not require software installation and updates on individual computers, saving both time and money.

Businesses are moving to virtualization more and more, due to the long-term savings in being able to eliminate computer hardware. VMware is a popular software system for setting up virtualization because of its versatility.

Multiple VM we can use in single Physical server consider as Virtualization for proper utilization of resources and better administration with reduce cost.

In computing, virtualization means to create a virtual version of a device or resource, such as a server, storage device, network or even an operating system where the framework divides the resource into one or more execution environments.

Virtualization is the creation of a virtual -- rather than actual -- version of something, such as an operating system, a server, a storage device or network resources

Its Like a Virtual OS you can download it on Oracle VM Virtualbox

Usually it was used for Linux and WIndows Server 

Example your Computer has Windows 10 OS if you install Oracle VM Virtual box you add Linux and Windows Server in one PC.