This document discusses cloud computing and software as a service (SaaS). It defines SaaS as software that runs as a single instance on demand via a web browser or client. Key advantages of SaaS include lower costs, automatic upgrades, and compatibility since all users have the same version. The document also discusses web services, web 2.0, and web operating systems. It notes that SaaS applications have lower barriers to entry and costs compared to locally installed software due to reduced distribution and maintenance costs.