What is IIS Express

IIS Express is a lightweight, self-contained version of IIS optimized for developers. IIS Express makes it easy to use the most current version of IIS to develop and test websites. It has all the core capabilities of IIS 7 and above as well as additional features designed to ease website development including:

  1. It doesn’t run as a service or require administrator user rights to perform most tasks.
  2. IIS Express works well with ASP.NET and PHP applications.
  3. Multiple users of IIS Express can work independently on the same computer.

Source: iis.net

What is Platform as a Service (PaaS)

With PaaS, you deploy your application into an application-hosting environment provided by the cloud service vendor. The developer provides the application, and the PaaS vendor provides the ability to deploy and run it. This frees up developers from infrastructure management, allowing them to focus strictly on development.

 

Source: Microsoft Azure Essentials