If you're at http://www.you.com/foo/bar.htm,

• to link to http://www.you.com/foo/loo/lar.htm, link to "/loo/lar.htm"
• to link to http://www.you.com/index.htm, link to "../index.htm"
• to link to http://www.you.com/foo/har.htm, link to "har.htm"

Remember: no spaces or other funny characters in file names or links.

And if you copy a link from one document to another, make sure you have the correct relative path in the new document!

(Same goes for images – their paths are also relative.)

So a link to "/loo/lar.htm" copied from http://www.you.com/foo/bar.htm to http://www.you.com/index.htm will not work – it needs to be "/foo/loo/lar.htm".

And if it's an image, it won't show up – you'll see this kind of thing:

or, if you've used an ALT for the image, you'll see this: