Cloud computing is a model, wherein pooling of available shared resources is done. It may mean data centre hosting and understood as utility computing or grid computing. Cloud computing is the latest technology considered now-a-days. Cloud computing uses the concepts of metered service i.e. pay-as-you-go, as per the requirement of the user. Cloud computing includes the concept of grid computing, utility in computing, and of course storage in cloud. In this paper, the authors present the introduction of cloud computing and emphasize on the security aspects of cloud computing.