This document discusses cloud computing. It defines cloud computing as storing and accessing data and programs over the Internet instead of a computer's hard drive. Some key benefits of cloud computing mentioned are achieving economies of scale, reducing infrastructure costs, improving accessibility and flexibility. The main components of cloud computing listed are applications, clients, infrastructure, platforms, services, and storage. Cloud computing layers discussed include storage, database, process, application, and infrastructure as services. Several major companies that provide cloud computing services like Amazon, Rackspace, Salesforce, Google and Microsoft are also listed.