What is a site map? 
A lot of sites use a site map to show visitors the structure of the site and where to find what kind of information. When made correctly, a site map can serve as an added navigation tool. Having a site map however is never an excuse for a less than usable navigation. A page that shows user the structure of a site on one page isn't a substitute for a navigation. Especially because a lot of users still don't know what a site map is and as a consequence aren't very inclined to click on it. Using a different term than site map is not a solution though. Site map is the most widespread and hence most recognizable term. It's no good making up your own terminology like for example Sun does with 'Site Index' or iWon with 'Site Overview'.

Goal 
The main goal of a site map is to visualise the structure of a site. Ideally, a site map is a simple representation of the structure of the site, consisting of a collection of links that shows users all the information in a single view. That way, users can easily see in which first or second level of the site to find which information. Because it is important that users can take in the information in the site map in a single view, this means that - for complex sites - the site map is not a complete index of the site. A site map should minimally consist of all the items of the first and second level of the site. This second level can mean the terms used in the second level of the navigation or, if there is only one level of navigation, the names of pages. It's very important not to forget certain elements of your navigation on your site map, like BBL does on the English version of its site by forgetting to mention the item 'Expats & non-residents' under the main navigation item 'PRIVATE'. When sites are very complex, sometimes it's worth considering to also add the third level of navigation though this is definitely the limit. When a site map shows users four or more levels of a site, they often lose the overview of the structure. To maintain that overview, it is advisable to keep the site map below three screen lengths in a resolution of 800 on 600.

Terminology 
The words and phrases used in your site map have to be identical to the ones you use in your navigation or page titles. If you start using different words, users find it hard to make a connection between the structure presented in the site map and the structure of the site itself. Also make sure that the words you use make sense to users and give them an indication of what to expect when they click on it. Site maps that not only contain the words from the navigation levels but also a lot of explanatory text, like E! Online for example, are not a good idea.

Plain text links 
In order to make it clear to users which part of the site they have already visited and which ones they haven't, it is best to avoid the use of images but instead opt for simple text links. That way, you can use different colours to indicate which links have already been visited and which ones haven't yet, like CDNOW does.

Where am I? 
The ideal site map not only gives users an overview of a site's structure but also indicates where the user was the moment he opted to go to the site map. A system that is comparable to the "You are here" indication on a map of a city or a mall.

Els Aerts & Karl Gilis

A more in depth version of this article has appeared in Tips & Advies Online Ondernemen, year 5, number 18 (Belgium and the Netherlands).