Currently, most of the activity in the virtualization world focuses on server virtualization —– the data centers or server farms. The three main types of server virtualization are:
Operating system virtualization (aka containers): Creates self-contained representations of underlying operating system in order to provide applications in isolated execution environments. Each self-contained environment (container) reflects the underlying operating system version and patch level.
Hardware emulation: Represents a computer hardware environment in software so that multiple operating systems can be installed on a single computer.
Paravirtualization: A thin software layer that coordinates access from multiple operating systems to underlying hardware.