This document discusses cloud computing and provides definitions from Forrester Research. It defines different types of cloud including Software as a Service (SaaS), Platform as a Service (PaaS), and Infrastructure as a Service (IaaS). It explains that the maturation of virtualization technology enabled compute clouds which created demand for storage and infrastructure clouds. It concludes that cloud computing involves virtualized compute power and storage delivered over the internet through programmatic interfaces and billed variably based on usage.