Abstract: Cloud computing basically involves delivering hosted services over the Internet to store, manage, and process data, instead of using local server or a personal computer. These services are broadly divided into three categories: Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS) and Software-as-a-Service (SaaS). In scientific terms, cloud computing is a synonym for distributed computing over a network which means the ability to run a program on many connected computers at the same time. Therefore it involves a large number of computers that are connected through a real-time communication network.
Keywords: Cloud, Public Cloud, Private Cloud, Hybrid Cloud, Federation of Cloud, Infrastructure as a Service Iaas, Platform as a Service Paas, Software as a Service Saas