It's the latest craze - take whatever you can think of in IT and networking, and add "as a service" to the end of it. Infrastructure as a Service (IaaS), Platform as a Service (PaaS) and Software as a Service (SaaS) are the three main types, and all the other xxx-as-a-Service types and aaS abbreviations can be classified as Infrastructure-based, Platform-based or Software-based.
