Infrastructure as a Service (IaaS) We take care of : Operating System, building/creating the application, and maintaining data, Host takes care of: Hardware, middleware, software requirements Platform as a Service (PaaS) We take care of : Building/creating the application, and maintaining data Host takes care of: Operating System, hardware, middleware, software requirements Software as a Service (SaaS) We take care of : Customizing the application Host takes care of: Everything else, having the software, maintaining data, Operating Systems, hardware, middleware, software requirements are handled by SaaS