Internet is on the edge of another revolution, where resources are globally networked and can be easily shared. Cloud computing is the main component of this paradigm in order to share the data, which renders the Internet in large repository where resources are available to everyone as services. Cloud computing typically begins with virtualization and is the ability to run the multiple operating systems on a single machine buy sharing all the resources that belong to the hardware. Thus in this paper after surveying some of the current best practice and relevant literature in this area, reviews of virtualization in context of methods and technique currently used for cloud computing are explored. This paper will identify the key ideas, trends, which involved for resource virtualization in cloud.