۱٫۱٫ What is cloud computing?

The National Institute of Standards and Technology’s (NIST) definition of cloud services is widely adopted, being rapidly available and scalable services provided on-demand from a shared pool of resources.1Thus it is a model “enabling ubiquitous, 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”. The three main recognised uses include Software as a Service (SaaS), Platform as a Service (PaaS), and Infrastructure as a Service (IaaS). SaaS is the most visible of cloud services – encompassing ‘free’ online email and social media services, as well as sharing of content stored “in the cloud” without download or installation required. The provision of platforms (PaaS) such as Google App Engine is useful to developers and those wishing to avoid the need for initial investment in software and hardware, but still requiring server management. Finally, infrastructure can be provided via IaaS directly to the wholesale user and more recently end-user. Data storage, network capability, and remote computing can be purchased alone or invisibly “layered” into platform and software service provision, and includes Amazon Web Services and its competitors.