This document discusses cloud computing. It defines cloud computing as a model that enables on-demand access to shared configurable computing resources over a network. The document outlines the evolution, need, characteristics, benefits, types of services, types of clouds, advantages and disadvantages of cloud computing. It provides examples of major cloud computing providers like Amazon Web Services, Microsoft Azure, Google Cloud Platform and others. The types of cloud services discussed are Infrastructure as a Service, Platform as a Service and Software as a Service. Public, private and hybrid cloud models are also mentioned.