What is Virtual Machine

The term virtual may refer to not physically existing. In the software terms, a virtual machine (VM) is a simulation of a physical system. Virtual machines are based on the physical (real) system architectures and provide functionality the same as a physical (real) world system. Virtual machines gives appearance and functions like any physical system. A simple calendar software application program which simulates the behavior of a real-world calendar is the best example of Virtual Machine.    

Examples:  

VMware  

kernel  

Cloud-Based Systems