The ability of cloud computing to offer solutions to the business IT challenges stated above is driving more organizations to use cloud computing as a key part of their IT infrastructure.
The National Institute of Standards and Technology (NIST) provides a definition of cloud computing.
Cloud computing is a model for enabling ubiquitous, convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction. This cloud model is composed of five essential characteristics, three service models, and four deployment models (https://csrc.nist.gov/publications/detail/sp/800-145/final).
The five essential characteristics of cloud computing are:
A public cloud is formed when a cloud provider makes computing resources publicly available over the internet or other broad network channels. In a public cloud, setup for a consumer is usually quick and easy. Users pay for resources used rather than for direct hardware. Some providers also charge a subscription fee. If more resources are needed, the cloud can instantly provide them. There is no need to install additional hardware or software. One of the concerns and barriers for organizations using the public cloud is data security and governance.
Private cloud describes a computing infrastructure privately held by an organization that has capabilities similar to a public cloud but is completely internal and therefore could be considered more secure based on an organization’s regulatory and compliance requirements. Virtualization provides many cloud-like resource allocation features. The addition of cloud management tools can be used to build a private cloud.
Almost every study shows that organizations desire to use a variety of cloud platforms across both public and private clouds resulting in a potentially complex multi-cloud strategy. As Jeff Clarke, vice chairman of products and operations of Dell Technologies, put it: “Cloud is not a destination; it’s an operating model." (https://www.livemint.com/technology/tech-news/why-michael-dell-is-betting-big-on-multi-cloud-strategy-1556592666769.html)