A sitemap is a list of pages of a web site accessible to crawlers or users. 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.
Most search engines will only follow a finite number of links from a page, so if the number of links is very large, the site map may be required so that search engines and visitors can access all content on the site.