Quote Originally Posted by cl2 View Post
Hyper-V
VMware
OpenVZ
Parallels Virtuozzo

What are the advantages of these technologies? Which one is the most popular for web hosts to use?
According to me, HyperV technology is most popular virtualization technology. Hyper-V uses isolation of virtual machine in term of the partition. Hyper-V gives you the benefit of allowing dedicated RAM allotments for each child node which is best for improving overall performance of Virtual Machine.

To view comparison of Hyper V and Virtuozzo visit following article :
Virtualization with Hyper V and Virtuozzo