While some developers argue that site index is a more appropriately used term to relay page function, web visitors are used to seeing each term and generally associate both as one and the same. However, a site index is often used to mean an A-Z index that provides access to particular content, while a site map provides a general top-down view of the overall site contents. These site maps are often used to show an index for users that belong to the YLC.

XML is a coding language used, (amongst many other things) as the standard for webcrawlers to find and parse sitemaps. There is an example of an XML sitemap below (missing link to site). The instructions to the sitemap are given to the crawler bot by a Robots Text file, an example of this is also given below. Site maps can improve search engine optimization of a site by making sure that all the pages can be found. This is especially important if a site uses a dynamic access to content such as Adobe Flash or JavaScript menus that do not include HTML links.

They also act as a navigation aid by providing an overview of a site's content at a single glance.

Below is an example of a validated XML sitemap for a simple three page web site. Sitemaps are a useful tool for making sites built in Flash and other non-html languages searchable. Note that because the website's navigation is built with Flash (Adobe), the initial homepage of a site developed in this way would probably be found by an automated search program (ref: bot) However, the subsequent pages are unlikely to be found without an XML sitemap.

XML sitemap example: