Updated 1/4/19
Question
You have heard of Azure's Serverless Function Apps. What are they and what do they do?
Answer
A Serverless Function App is a PaaS solution. As of 1/4/19 they support .NET or JavaScript code as if the code was run on a Windows environment. They will eventually support Java/Linux.
You can run a program without a server using Azure. It could potentially be accessible on the web or through other connectors to different Azure servers. You do not need to be concerned about the systems administration on the back-end. See this posting if you want to use an Azure Function.