Cloud computing is a type of service network that provides computing resources for users on-demand. These resources are composed as services by cloud service providers and delivered to the user, called the consumer. Cloud Computing services are broadly classified into three major categories namely Infrastructure as a Service (IaaS) where user is provided with storage, computation, networks and more of such hardware resources; Platform as a Service(PaaS) where user is provided with an environment to develop, test and deploy applications and services; and Software as a service (SaaS) where user is provided with a complete software package. A cloud computing system uses the Internet and open to general public is called the Public Cloud. On the other hand, a cloud computing system built by an organization and restricted to insiders such as employees or partners is called a private cloud. A combination of private and public cloud constitutes a hybrid cloud. Service providers establish data center to build and deliver services.
