Cloud computing is a model that provides on-demand access to a shared pool of configurable computing resources. It has characteristics of on-demand self-service, broad network access, resource pooling, rapid elasticity, and measured service. There are three main service models - Software as a Service (SaaS), Platform as a Service (PaaS), and Infrastructure as a Service (IaaS). The document then discusses Infrastructure as a Service (IaaS) specifically, describing Amazon EC2 as an example of IaaS and its key concepts such as AMIs, regions, storage options, networking, security, monitoring and auto-scaling.
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