Cloud Computing: What is it?

NIST describes cloud computing through on-demand access to shared configurable resources. Its model distinguishes essential characteristics, service models and deployment models. This vocabulary helps separate infrastructure, platforms and finished applications instead of treating every hosted service as equivalent.

Amazon’s EC2 limited beta offered virtual computing resources through web-service interfaces. It is one landmark in the evolution toward on-demand infrastructure, not a claim that one company invented all shared or networked computing. Earlier computing traditions also shaped the field.