This document defines and explains cloud computing. Cloud computing allows users to access software and storage over the internet rather than locally on their own computer. It discusses the history of cloud computing concepts dating back to 1950. The key components of cloud include clients, distributed servers located in datacenters, and a central server that administers the system. There are different service models depending on what is provided via the cloud. Cloud services can be deployed in public, private, community, or hybrid models. The popularity of cloud computing is due to advantages like reduced complexity, scalability, and not needing to purchase and maintain own software/servers.