The term Cloud computing comes from how the Internet has traditionally been symbolised in network diagrams and system designs using the image of a Cloud. In short cloud computing is the use of hosted resources located in large secure data centres to provide computer platforms, software, and information to end user devices, like the electricity grid. Cloud technology itself has been defined by the National Institute of Standards and Technology (NIST) as follows:
‘Cloud computing is a model for enabling convenient, on-demand network access to a shared pool of configurable computing resources… that can be rapidly provisioned and released with minimal management effort or service provider interaction. This cloud model promotes availability and is composed of five essential characteristics, three delivery models, and four deployment methods.’
It then gives the essential characteristics as:
• On-demand
• Ubiquitous network access
• Location-independent resource pooling
• Rapid elasticity
• Measured service
Another, more straightforward, example is the cloud as a commercial entity that enables users to purchase computer services and have them delivered as a service online.