Ok, how long have I been doing web design? And until this afternoon, if you would have asked me how to create a relative link to a file two directories up, I would have had to look it up or would have fiddled around with slashes and dots until it worked. The reason: I got started using Dreamweaver.
Anyway, I finally did look it up. The rule?
./ <- current directory. Handy if you want to link to the index page without to use something like 'index.html'
../ <- parent directory
source:
webmasterworld.comThe other reason I never mastered this was I started working in PHP and was more concerned on creating relative links from a variable defined root level. In that case -- say where you move a site from a subdirectory on your local server to the root directory of a production server -- these kinds of links are not that handy.