What does express mean for a proxy?

Question

proxy

I read the express js docs and there is an article "when running an express application behind a proxy server" how is it, and what is it about in general, what is it for?

Answer 1

Most likely, this means using a reverse proxy, such as nginx.
The reasons may be different, for example, to combine several physical servers into one virtual one, speed up the return of statics, make TLS or HTTP / 2 unified support, route requests based on some specific logic, etc.