Understanding email addresses

A while back, an acquaintance of mine asked me to explain how email addresses work. Although the concepts are easy enough to understand, he’d never really “got it”, and so asked me for help.
 
Email addresses are built up from three parts; a recipient, a server and a top level domain node (TLD). The address is formatted much like this: recipient@server.tld. If this was an address for regular mail, it’d look like this:
Recipient
Server
TLD
 
It’s easiest to think of the server part of the address as the street name and number, and the TLD as the zip code.