What is Cloud?

Essential characteristics of a cloud according to NIST Special Publication 800-145:

  1. On-demand Self-Service. Can provision capabilities as needed without requiring human interaction with each service provider.
  2. Broad Network Access. Capabilities are available over the network and accessed through standard mechanisms that promote use by heterogeneous thin or thick client platforms (e.g., mobile phones, laptops, and workstations).
  3. Resource Pooling. The provider's computing resources are pooled to serve multiple consumers using a multi-tenant model, with different physical and virtual resources dynamically assigned and reassigned according to consumer demand. There is a sense of location independence in that the customer generally has no control or knowledge over the exact location of the provided resources but may be able to specify location at a higher level of abstraction (e.g., country, state, or datacenter). Examples of resources include storage, processing, memory, and network bandwidth.
  4. Rapid Elasticity. Capabilities can be elastically provisioned and released, in some cases automatically, to scale rapidly outward and inward commensurate with demand. To the consumer, the capabilities available for provisioning often appear to be unlimited and can be appropriated in any quantity at any time.
  5. Measured Service. Cloud systems automatically control and optimize resource use by leveraging a metering capability at some level of abstraction appropriate to the type of service (e.g., storage, processing, bandwidth, and active user accounts). Resource usage can be monitored, controlled, reported and billed providing transparency for both the provider and consumer of the utilized service.


  1. On-demand Self-Service: Create and terminate resources through UI/CLI without human interaction.
  2. Broad Network Access: Access resources over any network and any device using standard methods.
  3. Resource Pooling: Due to combining of resources, the provider can offer resources at a lower cost.
  4. Rapid Elasticity: Automatically scale resources up and down based on demand.
  5. Measured Service: Usage of resources is measured and billed for what you consume.