Cloud computing is a style of computing in which dynamically scalable and often virtualized resources are provided as a service over the Internet. Users need not have knowledge of, expertise in, or control over the technology infrastructure in the "cloud" that supports them.
The concept generally incorporates combinations of the following:
* infrastructure as a service (IaaS) * platform as a service (PaaS) * software as a service (SaaS) * Other recent (ca. 2007–09) technologies that rely on the Internet to satisfy the computing needs of users. Cloud computing services often provide common business applications online that are accessed from a web browser, while the software and data are stored on the servers.
The term cloud is used as a metaphor for the Internet, based on how the Internet is depicted in computer network diagrams and is an abstraction for the complex infrastructure it conceals.
The first academic use of this term appears to be by Prof. Ramnath K. Chellappa (currently at Goizueta Business School, Emory University) who originally defined it as a computing paradigm where the boundaries of computing will be determined by economic rationale rather than technical limits.