What the anchor tag contains is the hot text or object that you click on. One that refers to a file at the same site is called relative.
Relative links are the most confusing.
Two of these are in the same directory. If you write relative links you can have a mirror of your site on your harddrive and the links you create on the harddrive will still work when they are uploaded to the site. If you change servers, you can port your entire site over to the new machine and all your local links will still work. Links from files in subdirectories up to parent directories require the filename be preceded by two dots and a slash for each parent directory higher up the file tree.