PaaS is one step above IaaS. It provides a platform where you can develop and deploy software. It makes development, testing, and deployment simpler, faster, and more cost effective by providing the programming language to interact with services, databases, servers, and/or storage without having to deal with the infrastructure in which it is being used.

Since PaaS is built on top of virtualization technology, the vendor of such services provides the physical/virtual environment with frameworks and runtimes to manage your applications and data. Google App Engine, Red Hat's OpenShift, and Heroku are some examples of well-known PaaS services. Azure App Service and Azure CDN are examples of PaaS on Azure.