The document discusses cloud computing and provides definitions and characteristics. It describes cloud computing as a technology that delivers on-demand IT resources over the internet on a pay-per-use basis. The key characteristics of cloud computing include scalability, reliability, security, flexibility, and serviceability. There are three main types of clouds based on deployment - public, private, and hybrid clouds. The document also outlines the three main service models of cloud computing - Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS).