This document presents an introduction to cloud computing. It defines cloud computing as using remote servers and the internet to maintain data and applications. It describes the characteristics of cloud computing including APIs, virtualization, reliability, and security. It discusses the different types of cloud including public, private, community, and hybrid cloud. It also defines the three main cloud stacks: Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS). The benefits of cloud computing are reduced costs, improved accessibility and flexibility. Cloud security and uses of cloud computing are also briefly discussed.