I am new to Docker and found one thing I don't understand: I downloaded the image jwilder/nginx-proxy from the Github repo nginx-proxy/nginx-proxy and ran it with docker-compose up. This will bring on a new network nginxproxy_default, which the new container is connected to, although the docker-compose.yml does not have a network specified. I searched all files in the repository but I didn't find any place where this network is configured, so where does it come from?
It is a default network created automatically by docker-compose. Read more here.