A self-service, pay-as-you-go model of providing computing resources to an organization or to the general public.
Cloud Computing evolved from existing technologies such as a fast and reliable Internet, virtual operating environments including virtual machines and virtual storage and is provided to users as a utility service. Utilities such as water and electricity are provided and purchased as needed. A cloud resource is provided on-demand and is charged by usage. Cloud customers can access a wide variety of computing services but customers pay only for what is used.
Services provided by cloud providers include compute, storage, applications, network resources, internal resources such as IP addresses and store-and-forward queues as well as infrastructure services like databases, web servers, load balancers and security systems.