Cloud computing is the on-demand availability of computer system resources, such as data storage (cloud storage) and computing power, without direct active management by the user. The term is generally used to describe data centres available to many users over the Internet.
Large clouds often have functions distributed over multiple locations from central servers. Clouds may be limited to a single organization (enterprise cloud) or be available to multiple organizations (public cloud).
Cloud computing relies on the sharing of resources to achieve coherence and economies of scale. Cloud computing allows companies to avoid or minimize up-front IT infrastructure costs. Besides, cloud computing allows enterprises to get their applications up and running faster, with improved manageability and less maintenance, which enables IT teams to more rapidly adjust resources to meet fluctuating and unpredictable demand, providing the burst computing capability: high computing power at certain periods of peak demand.
The concept incorporates infrastructure as a service (IaaS), platform as a service (PaaS), and software as a service (SaaS), as well as Web 2.0 and other recent technology trends that have the common theme of reliance on the Internet for satisfying the computing needs of the users.
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.
