why must I add the port number

[Birte Glimm]

Hi, I have installed tomcat as a standalone webserver on Win 2000. 
To get a page or a servlet I have to type e.g. 
http://localhost:8080/examples/servlet/helloWorldExample
but why must I include the port? Isn`t it the standard http port as in all other 
webservers? If the port number is missing I get "Cannot find server" and "The page 
cannot be displayed"

Thanks

Birte Glimm