Here is an example of an absolute link to the Yahoo web portal. This will take me to one place, and only one place on the whole internet!
The following link is a relative link. It takes us to a page that exists in the same directory. If this were published to a web server, it would be on the same web server. Let's go to it.
On the same page as the above relative link, I placed an anchor down on that page. Using this link I can go straight to the anchor on that page.
The following link should bring up your e-mail program so you can send your wonderful instructor E-mail.
The next link will take you to the rec.arts.theater.musicals Usenet newsgroup. It won't work unless you have a Usenet client configured on your computer, and recognized by your browser.