On-Premises: As you start on the left in the traditional on-prem configuration you are responsible for all layers of IT from the networking stack all the way up to the applications which are being provided. You may also be responsible for the data center, power, Internet service, and other underlying aspects.
Infrastructure as a Service: In IaaS (Take & Bake) the cloud vendor is responsible for the stack from networking through virtualization and your IT team is responsible for the Operating System (OS) through the applications. Common uses of IaaS are testing environments, development environments or hosting of a website.
Platform as a Service: In PaaS (Pizza Delivered) the cloud vendor is responsible for the networking layers through the runtime layer and your IT team is responsible for the data and the applications. PaaS is commonly used to test, build and deploy applications for an organization.
Software as a Service: In SaaS (Dining Out) the cloud vendor is responsible for all layers from the networking through to the application layer. A common example of SaaS is a web-based email service such as Outlook, Hotmail or Gmail.
