Summary: The term “Cloud Computing” refers to any “computing capability that is delivered as a service over the Internet. While there is no authoritatively accredited definition of the concept, one of the most frequently used definitions is the one given by Gartner, who describe cloud computing as “a style of computing where massively scalable IT-related capabilities are provided ‘as a service’ across the Internet to multiple external
customers.”

This briefing paper will explain some of the key characteristics and delivery levels of current development and implementations that provide a basis for understanding cloud computing and the ongoing discussion about it.

[pdf http://publications.cetis.org.uk/wp-content/uploads/2011/10/Cloud_Computing.pdf]