Cloud Computing is the on-demand availability of computer system resources, especially data 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, predominant today, often have functions distributed over multiple locations from central servers.. If the connection to the user is relatively close, it may be designated an edge server.
Clouds may be limited to a single organisation (enterprise clouds), or be available to multiple organizations (public cloud). Hybrid cloud is a composition of a public cloud and a private environment, such as a private cloud or on-premises resources.
Cloud computing relies on sharing of resources to achieve coherence and economies of scale.
Advocates of public and hybrid clouds note that cloud computing allows companies to avoid or minimize up-front IT infrastructure costs. Proponents also claim that cloud computing allows organisations to get their applications up and running faster, with improved manageability and less maintenance, and that it 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.
Cloud providers typically use a “pay-as-you-go” model, which can lead to unexpected operating expenses, if administrators are not familiarized with cloud-pricing models.