In 2011, the United States National Institute of Standards and Technology (NIST) defined cloud computing as follows:

“A model for enabling ubiquitous, convenient, on-demand network access to a shared pool of configurable computing resources, such as networks, servers, storage, applications, and services, that can be rapidly provisioned and released with minimal management effort or service-provider interaction.”

Cloud computing has five essential characteristics, three service models, and four deployment models.