My Website is on a remote server, and on my computer, which is also being used as a server with xampp installed. Which files will the browser access if I just type www.mydomain.com in the address bar? The domain name is pointed to the remote server, but xampp is also configured with the domain name.
Your browser will go to your remote machine if that's where the DNS record points to.
Even though you may have configured the same site as a virtual host on your local xampp install, your browser doesn't know that.
If however, you have edited your hosts file or similar, to point to you local IP if you will reach the local copy.
This depends completely on name resolution - having the web server configured in one way or another will not influence the decision on where the request will go.
What this means in practice is that if you've configured your hosts file or your internal DNS to point that name to the local server, then it will get the request; otherwise, it will resolve the name in the public DNS hierarchy and send the request to the server there - which should be the remote server.