The most common definition for platform as a service describes a layer of technology that assists developers in the deployment and scale of their applications. You’ll see those two words, “Deploy” and “Scale,” echoed throughout the marketing of many of the prominent PaaS vendors.
Another familiar refrain you’ll hear with PaaS is, “if you have to touch the operating system, it’s not PaaS.” In other words, if Infrastructure-as-a-Service (IaaS) hides the physical machines, PaaS hides the virtual machines and operating systems. So one of the values of PaaS is eliminating the need for the application owner to maintain the underlying operating environment.
But remember, PaaS is supposed to cater to developers.