How links work with HTML and URLs

Say you have a document located at http://community.nbtsc.org/~user/specialstuff/quux.

Then, in your HTML for that page, if you link to grobnitz, then the URL will end up being http://community.nbtsc.org/~user/specialstuff/grobnitz. The browser sees no start of a complete URL nor a / to start things, it takes everything up to the last / in the URL of the document, and adds your link to that.

If you link to ../somewhereelse/foo or to /~user/somewhereelse/foo then the URL will end up being http://community.nbtsc.org/~user/somewhereelse/foo. In this case, if the browser sees /~user/somewhereelse/foo in the link, it chops the URL of the document off right after the host part — in this case, community.nbtsc.org. It adds what you specify, and you get the result. If you put in ../somewhereelse/foo, then it sees "no /" like before, but then, the .. cancels out one part between slashes, in this case, the /specialstuff/.

If you link to /gringo, then the URL will end up being http://community.nbtsc.org/gringo.

And, if you link to http://www.google.com, the URL will be http://www.google.com.