This document provides an introduction to cloud computing. It defines cloud computing as a model that enables on-demand access to a shared pool of configurable computing resources over the internet. It describes the essential characteristics of cloud computing including on-demand self-service, broad network access, resource pooling, rapid elasticity, and measured service. It also outlines the different deployment models including private cloud, community cloud, public cloud and hybrid cloud. Additionally, it discusses the different service models of SaaS, PaaS and IaaS and presents the NIST guidelines for implementing cloud computing solutions.