Cloud computing ---Head in the Cloud, Feet on the Ground --Architectural Journal

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 Cloud computing is Internet ("cloud") based development and use of computer technology ("computing"). It is a style of computing in which typically real-time scalable resources are provided “as a service” over the Internet to users who need not have knowledge of, expertise in, or control over the technology infrastructure ("in the cloud") that supports them.

The concept incorporates software as a service (SaaS), Web 2.0 and other recent, well-known technology trends, in which the common theme is reliance on the Internet for satisfying the computing needs of the users. An often-quoted example is Google Apps, which provides common business applications online that are accessed from a web browser, while the software and data are stored on Google servers.

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.