A sitemap is an easy way for webmasters to inform search engines about pages on their sites that are available for crawling. The sitemap protocol format is defined at http://www.sitemaps.org/protocol.html
Sitemap can be either a document in any form used as a planning tool for web design, or a web page that lists the pages on a web site, typically organized in hierarchical fashion. This helps visitors and search engine bots find pages on the site.
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.
XML is a document structure and encoding standard 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.
