Virtualisation is the process of creating a virtual version of a physical object.
Virtualisation is of three types primarily: 1. Hardware Virtualisation - Based on simulating real hardware. This can be used to run a complete operating system. This can be further subdivided into full and paravirtualisation.
Desktop Virtualisation - It is the concept of separating the logical desktop from the physical machine.
Operating system level virtualisation (also called as containerisation) - It is the operating system feature in which the kernel allows the existence of multiple isolated user-space instances.