What on earth is nginx? The difference with IIS?

I have been using the C-sharp language to develop BS programs. IIS is my WEB server. I don"t know what IIS is here. Because it can handle requests and interact with the back end at the same time.
recently, when I was separated before and after learning, I saw that Nginx, itself would be a little bit python,. Suddenly, I saw that nginx was only responsible for processing the request, and then sent the request to the APP server. I felt that it might be the server that had contact with the background, such as uwsgi. So
can I think of what IIS can do as what nginx+uwsgi can do?
because IIS can process requests as well as interact with each other in the background, is the C-sharp code I wrote placed on IIS after release, or is the
IIS handling requests, while the piece of code that really handles the code is .net FrameWork??

Aug.20,2021

I think it may be the server that has a connection with the background, such as uwsgi

uwsgi is not required, it just adds a "gateway protocol" in the middle.

can I think of what IIS can do as what nginx+uwsgi can do?

what iis can do at the "network level" is what nginx does, without thinking about uwsgi.

IIS handles requests, while the one who really handles the piece of code is .net FrameWork?.

I'm not sure. Maybe iis is not only a "reverse proxy server", but also a "container".

first of all, you need to be clear about network protocols, which may include http, and other gateway protocols, such as fastcgi, wsgi.
then, you have to understand why it is necessary to create a gateway protocol in the context of the emergence of the gateway protocol.
next, take a look at the application layer code you write and what protocol it is dealing with after deployment. C-sharp is not clear, in Python, the deployment is different, the application layer directly deals with different protocols, it may be wsgi, it may be http directly.
finally, in the case of nginx and Python, the roles of nginx vary from deployment to deployment. It can directly reverse proxy and forward http. It can also be used as a web service and transferred out to a gateway protocol.

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