SaaS

Software as a Service delivers fully functional applications over the internet, with the cloud provider managing every layer: hardware, networking, operating system, runtime, middleware, and the application itself. The customer simply uses the software through a browser or thin client. An AWS example is Amazon WorkMail, and many third-party SaaS products are available through AWS Marketplace. Under the shared responsibility model the provider handles nearly everything, leaving the customer responsible mainly for their own data and user access. This contrasts with IaaS, where the customer manages the OS upward, and PaaS, where the customer manages only their application and data.