It is utilized to unambiguously describe and identify both the protocol used by and the location of Internet resources. URLs describe the protocols and locations of Internet resources without regard to the particular Internet client software the user is employing to access them. This common syntax is dependent on the scheme. Similarly, this is useful for instructing the end-user on how to log into a remote telnet sessions.
Ports represent a section of a communications band available from the Internet protocols.
Think of them like telephone number extensions. You know this means to call the 800 number and ask for extension 1234. In most cases, the port number is assumed given a particular scheme. For example, the telnet protocol assumes you want port 23. Gopher assumes port 70.