sorry if this may seem dumb , but.....

Do web services run on port 80, or do they, by default, use another port?
If so, then is this configurable?

Cheers

in order for Microsoft services to function correctly they need their own unique port... for example

HTTP (Web): Port 80
POP3: Port 110 (i think)
SMTP: Port 25 (i think)
Telnet: Port 23

so when you want to access a particular service, you send a message to the computer on that port that the service is running on

There's two definitions of web services. The one Mart was referring to is a publish/subscribe service that usually runs over port 80/443 but can actually publish from or subscribe to any port you want. RSS news feeds are a simpler, older form of this. Google and Amazon have newer XML-based web services.

The type of web services pmormr is referring to are the traditional net services. By convention, the bottom 1024 ports are reserved for the net and some services have been traditionally assigned to specific ports as pmormr noted. You can set up your web server to use different ports, but your client programs have to know this and many are not configurable.

Changing stardard ports for specific funtions to something non-standard is a common security technique - e.g. some db's use specific ports for remote maintenance. It's a good practice to set it up for a different port than what comes out of the box. Many sites also configure a different port for telnet, restricted shell, etc.