This document provides an overview of cloud computing, including what it is, computing needs it fulfills, perspectives on cloud architecture and types of clouds, drivers and barriers to adoption, and examples of top cloud computing providers. The key points made are that cloud computing provides dynamism, abstraction, and resource sharing; examples include Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS) models; and factors driving adoption include availability, collaboration, and scalability while barriers include security, reliability and vendor lock-in.