Most websites have many inter-linked pages and links to other people's websites, not to mention links to non-html documents. It is easy for any visitor to get lost, and in particular for disabled people. This lesson covers the importance of a clear site map as part of your navigation system.
For disabled people the site map is often the first page they look for on your website. A properly constructed site map provides a logical overview of your site that enables the user to understand what the site is trying to do as well as providing direct links to all the information. It is much more useful than even the best search facility (see search options below). A good site map provides a reliable and secure starting point for anyone who has problems navigating your site. It is the one place they can return to in order to get an overview of the site and some indication of where they have already been (links to visited pages should have changed colour or style).
Wherever possible site maps for large web sites should be organised conceptually rather than alphabetically. Many of your visitors will not have the same vocabulary as you, so a large A to Z index is not really much help. For example, suppose I want to find out what day my dustbins are emptied by the local council. Do I look under "D" for dustbins, "E" for environmental Services, "R" for refuse collection, or "W" for waste management etc.? Unless you put the appropriate link under all these alphabetic headings some visitors will struggle to find the information they need. Much better to first catagorise your services under general, informative headings such as "Environmental services - parks, allotments, street cleaning and waste management" and then list the relevant options.
If you are running a very large website, such as a local government site, you will have a number of different sections within your site. Each of these sections might require its own "site map" so that visitors can get just the most relevant links to their current area of interest. Each departmental site map should, of course, be accessible from a "top level" site map as well as from links on each page within the departmental section. The examples below show two common approaches to departmental site maps. On the left is a context rich index of sections that guide the visitor to areas of interest. On the right is a "Link-text" index consisting solely of links to pages within each section. Which type of approach is most suitable will depend upon your target audience and the complexity of your content. If most of your users are "first time visitors" then the context rich approach is best, even though it may involve an extra "click" to get to the required information. People who use the site frequently, and understand your terminology, will benefit most from the second example. However these are primarily "usability" issues. From an accessibility point of view both systems are effective providing that the text used for the actual link is relevant and meaningful.
It is important to ensure that each of the above site maps is constructed using the correct HTML heading codes. This means that a blind user can list the sections (Bereavement Services, Benefits, Children and Young people, Community Information etcetera) and jump straight to the section of interest. Without proper headings a blind user has to listen to the whole index to be certain of finding the information they require, this can take a long time.
Something to avoid
An interesting alternative to a listed catalogue of pages is a diagramatic concept "imagemap" as shown below. For a visual user with good mouse control this might be useful, but blind users and people who need to use the keyboard for navigation will find this type of site map almost impossible to understand or access. If you do use this idea then you MUST provide an alternative text based version that everyone can use.
Two or three click to any content
The idea that all your content should be available within 2 or 3 click from any page is a useful guide, but it should not get in the way of presenting logical routes to information, nor should it encourage you to create overly complex pages. The key to a usable (and accessible) navigation system is to make it logical and intuitive in structure. However, by providing a detailed site map with a link to it at the top of every page on your site does mean that you have provided a system that allows anyone to find the information they need within two or three clicks without cluttering up content pages with multiple links.
Content Management generated site maps
If you use a content management system (CMS) that generates a site map for you automatically you must check that the output makes sense to your visitors. Most CMS generates the site map text by copying the individual page <title> text, so make sure that page titles really do reflect the content of the page.