Simplest C# web server

Currently I am working on my university project with c#. The task is to create the simplest c# web server which can respond to GET request. However there are some requirements:

1) Use Socket class

2) Realization of your own HTTP protocol

I found many examples: Simple C# Http/TCP Server , C#: How to execute a HTTP request using sockets? and so on.

But still didnt understand why the realization of HTTP protocol is needed. Why should I use it? Is it necessary? Maybe you can share some examples. For any advice or information I will be grateful for eternity.

Thanks for help.