There are many virtualization technologies are available in the market today, some of them are OpenVZ, Xen, KVM and VMware, you can understand about all these technologies.
It is an operating system level virtualization technology based on linux kernel and it allows a physical server to run multiple operating systems. It creates multiple secure and isolated linux containers on a single physical server, each container performs as a standalone server and a container can independently reboot. It is a free service and runs only linux based operating systems such as Fedora, Debian, Centos and Gentoo.
Xen is an open source software, it allows multiple operating systems to run on a single physical computer by using a layer called a hypervisor. The Hypervisor is a program that allows multiple operating systems to share a single hardware. Xen supports Linux kernels through an approach called paravirtualization. It is used for both linux and windows.
KVM stands for kernel based virtual machine, built for linux OS that enables linux to work as a hypervisor to run multiple virtual machines. It is designed to operate on x86-based processor architecture. It is free and supports Linux, windows, salaries and BSD guests, It is the basis for IBM’s and Red hat’s Linux virtualization technologies, it is the most used technology in the OpenStack cloud. OpenStack is a global collaboration of developers and technologists to produce an open cloud computing platform.
It is Cloud computing and virtualization software for x86 compatible computers, it is based on ESX/ESXi bare metal hypervisor. VMware ESX and ESXi can be deployed as part of the VMware infrastructure to empower centralized management for enterprise desktops and data center applications. VMware server works with Linux, Windows, Solaris and Netware. It is the most mature virtualization and most expensive also.
Eventually Virtualization technology employed by virtual private servers, whereby a physical server divided into virtual divisions, and these technologies provides you higher reliability and greater performance.