The document defines cloud computing and its key characteristics, service models, and deployment models. Specifically, it provides definitions for cloud computing and its essential characteristics of on-demand self-service, broad network access, resource pooling, rapid elasticity, and measured service. It also describes the three cloud computing service models of Software as a Service (SaaS), Platform as a Service (PaaS), and Infrastructure as a Service (IaaS). Finally, it outlines the four deployment models of private cloud, public cloud, hybrid cloud, and community cloud.