What does Amazon use for virtualization?

EC2 uses Xen virtualization. Each virtual machine, called an "instance", functions as a virtual private server. Amazon sizes instances based on "Elastic Compute Units". The performance of otherwise identical virtual machines may vary. read more

The advantage of this is that HVMs can use hardware extensions which provide very fast access to underlying hardware on the host system. Paravirtualization, on the other hand, is a lighter form of virtualization. This technique is fast, and provides near native speed in comparison to full virtualization. read more

AWS Documentation » Amazon EC2 » User Guide for Linux Instances » Amazon Machine Images (AMI) » Linux AMI Virtualization Types Linux AMI Virtualization Types Linux Amazon Machine Images use one of two types of virtualization: paravirtual (PV) or hardware virtual machine (HVM). read more