“Cloud computing” refers to delivering hosted services over the Internet. The services tend to be divided into three categories: infrastructure-as-a-service (IaaS), platform-as-a-service (PaaS), and software-as-a-service (SaaS). A cloud service has characteristics that differentiate it from traditional hosting. It is sold on-demand, is elastic – so the user can have as much or as little of the service they want – and is fully managed by the provider.Recent innovations in virtualization, as well as improved access to high-speed Internet, have accelerated the growth of cloud computing.”
A cloud can be either public or private. A public cloud sells services to anyone on the Internet; a private cloud is a data center or proprietary network that supplies hosted services to a restricted number of people. If a service provider chooses public cloud resources to create their own private cloud, the result is a virtual private cloud. Whether public or private, the goal of cloud computing it to provide scalable and easy-to-access computing resources and IT services.
updated February 15, 2012