No — that prefix tells the OS which application to direct the address to.

The www., ftp., mail., etc. are on the server side, so the client gets directed to the correct computer owned by the domain owner.

To some degree, this quickly became irrelevant when virtual hosting became a thing; you could have something watching on the server side that would see an attempt to connect to port 80 or port 443, check the domain the client is looking for, and redirect them to the right internal or external IP address.

With the onset of CDNs, it became even less meaningful since load and availability balancers will now decide what computer will eventually receive the request.

All you really need is the URI (https://) and the port (:443) and everything else can be a black box.

Why don’t we see :80 and :443 on URLs anymore? Because a web browser, when it handles the URI request, auto-maps to the default ports for that URI unless it is explicitly told to use another.

As a result, you can enter example.com into a browser address bar, and you’ll automatically be taken to guest@www.example.com but all you’ll see on the browser bar is example.com.