Cloud computing is the next generation in computation. People can have everything they need on the cloud. Cloud computing is the next natural step in the evolution of on-demand information technology services and products. The Cloud is a metaphor for the Internet, based on how it is depicted in computer network diagrams, and is an abstraction for the complex infrastructure it conceals. By using such a “cloud,” you could conceivably access your organization’s systems from anywhere using virtually any Internet-ready device – with no need to load software onto your computers, or station IT personnel in data-center locations, or otherwise build your own IT infrastructure.

First let us understand what is a Cloud?
“A Cloud is a type of parallel and distributed system consisting of a collection of inter-connected and virtualized computers that are dynamically provisioned and presented as one or more unified computing resource(s) based on service-level agreements established through negotiation between the service provider and consumers.”

Various definitions of cloud computing is available, few of them are mentioned below:
Forrester’s definition of Cloud Computing:
“A pool of abstracted, highly scalable, and managed compute infrastructure capable of hosting end-customer applications and billed by consumption.”

Wikipedia definition of Cloud Computing:
“Cloud computing refers to the use of Internet (“cloud”) based computer technology for a variety of services. It is a style of computing in which dynamically scalable and often virtualised resources are provided as a service over the Internet.”

According to the IEEE Computer Society Cloud Computing is:
“A paradigm in which information is permanently stored in servers on the Internet and cached temporarily on clients that include desktops, entertainment centres, table computers, notebooks, wall computers, handhelds, etc.“

In simple words, “Cloud computing is computing available at will, by a variety of devices, wherever and whenever it is needed”.