There are few things to add to the title.
Suppose we have a domain
foo.com and a domain
bar.com and we want the first to be served by apache and the second to be served by nginx (both running on the same machine, please consider the possibility to use also other web servers, like lighthttpd), and we want them to be accessible just writing the URL and without specifying any port (at least on client side, but a redirect on server side would be acceptable).
Is that possible? How to accomplish something like that? I don't know where to start and googling I can only find how to host multiple domain on the same server... that is not what I'm looking for.