This document discusses virtualization in cloud computing. It begins with an abstract that introduces cloud computing and virtualization and how organizations are implementing these technologies to reduce costs. The document then discusses how virtualization is the basis for delivering infrastructure as a service in cloud computing by separating hardware constraints. It provides examples of major cloud computing service providers like Google, Amazon, and Microsoft and compares their various services. Finally, it discusses techniques for virtual machine placement in data centers and some examples of virtual labs.