There's a lot of confusing terms in the Cloud space. And that's not counting the term "Cloud." ;) IaaS (Infrastructure as a Services) - Virtual Machines and stuff on demand. PaaS (Platform as a Service) - You deploy your apps but try not to think about the Virtual Machines underneath. They exist, but we pretend they don't until forced. SaaS (Software as a Service) - Stuff like Office 365 and Gmail