The cloud stack has seven levels now, it's not just IaaS, PaaS, SaaS Every course still teaches three boxes. The market moved on about eighteen months ago. Every course still teaches three boxes: IaaS, PaaS, SaaS . The market stopped matching that picture about eighteen months ago. The old diagram was good. It answered one question well: how much of the server is my problem? Rent a machine and all of it is yours. Push code to a platform and most of it is theirs. Buy finished softwar...