Cloud computing is a model that offers on-demand access to a shared pool of configurable computing resources, characterized by self-service, resource pooling, and measured services. It includes three service models: Software as a Service (SaaS), Platform as a Service (PaaS), and Infrastructure as a Service (IaaS), each catering to different consumer needs and control over applications. The document further discusses deployment models, advantages, and highlights specific platforms such as Amazon EC2 and Hadoop for big data processing.