This document provides an introduction to cloud computing, including definitions, characteristics, service models, deployment models, and virtualization concepts. It defines cloud computing as storing and accessing data and programs on remote servers hosted on the internet. The main service models are infrastructure as a service (IaaS), platform as a service (PaaS), and software as a service (SaaS). The primary deployment models are public cloud, private cloud, hybrid cloud, community cloud, and multi-cloud. Virtualization allows for the sharing of physical resources and is key to cloud computing.