The concept of a virtual machine (VM) is simple, really: it’s a virtual server that emulates a hardware server. A virtual machine relies on the system’s physical hardware to emulate the exact same environment on which you install your applications. Depending on your use case, you can use a system virtual machine (that runs an entire OS as a process, allowing you to substitute a real machine for a virtual machine), or process virtual machines that let you execute computer applications alone in the virtual environment.