Definition of Cloud Computing

NIST defines cloud computing through these five essential characteristics:

• on-demand self-service
• broad network access
• resource pooling
• rapid elasiticity
• measured service

In addition to these characteristics, the Cloud Security Alliance also highlights multi-tenancy as an important element for cloud computing.

Cloud computing architecture can be visualized through models such as:

• SPI Model
• Cloud Cube Model

References:

http://csrc.nist.gov/publications/nistpubs/800-145/SP800-145.pdf

https://cloudsecurityalliance.org/guidance/csaguide.v3.0.pdf