It makes maintaining a menu very easy, without having to resort to server-side includes, scripting or frames. Pages are cacheable and can be bookmarked.

Basically, you start out writing 'bare' HTML pages, without HTML, HEAD or BODY tags, such as you'll find in the source directory of this website, take for example the one for this page, src/html-menus.html. If you look at the source, you'll see you'll see some special comment tags:

<!-- DECO TITLE       = "Menu generator for static HTML pages"
          DESCRIPTION = "A set of Perl scripts to generate menus in HTML pages" 
          KEYWORDS    = "HTML, menu, static, generate, automatic" -->

<!-- MENU PARENT="Software" TITLE="HTML menus" URL="FILE" -->

Both pseudo-tags (DECO and MENU) allow certain attributes, just like real HTML tags.

The idea is that you feed pages with that information first through decorate.pl, which creates decorated but menuless pages in a temporary directory, like this one.

You see there the decorared page, without the <!-- DECO --> pseudo tags, but with the <!-- MENU --> ones still present. You'll also notice an <!-- INSERT_MENU -->, which is part of the template embedded in decorate.pl.

The last step is feeding the pages in the correct order through menuize.pl, which builds a tree-like menu from the PARENT and TITLE attributes of the MENU tags, and inserts the generated menu with the correct item selected in the place of <!-- INSERT_MENU -->, producing the final output.

See the shell scripts mentioned above on how to do this. The end result is a website such as this one.