A site map (or sitemap ) is a list of pages of a web site .
There are three primary types of site map:
- Site maps used during the planning of a Web site by its designers .
- Human-visible listings, typically hierarchical, of the pages on a site.
- Structured listings intended for web crawlers such as search engines .
Types of site maps
Sitemaps can be addressed to users or to software. Many sites have user-visible sitemaps which present a systematic view, typically hierarchical, of the site. These are intended to help visitors find specific pages, and can also be used by crawlers. Alphabetically organized site maps, sometimes called site indexes, are a different approach.
They aussi act as a navigation aid  by providing good year overview of a website’s content at a single glance.
Google introduced the Sitemaps protocol so web developers can publish lists of links from across their sites. The basic premise is that some sites have a large number of dynamic pages that are only available through the use of forms and users. The Sitemap files contains URLs to these pages so that web crawlers can find them. Bing , Google , Yahoo and Ask now Jointly supporting the Sitemaps protocol.
Since the major search engines use the Sami protocol,  Having a Sitemap lets em-have the updated page information. Sitemaps do not guarantee all links will be crawled, and being crawled does not guarantee indexing.  Google Webmaster Tools allow a website owner to upload a sitemap that Google will crawl, or they can accomplish the same thing with the robots.txt file. 
XML Sitemaps have replaced the older method of “submitting to search engines” by filling out a form on the search engine’s submission page. Now web developers submit to Sitemap directly, or wait for search engines to find it. Regularly submitting an updated sitemap when new pages are published by the author. 
Benefits of XML sitemap to search-optimize Flash sites
Below is an example of a validated XML sitemap for a single page. Sitemaps are a useful tool for making websites built in Flash and other non-html languages searchable. If a website is built with Flash, an automated search program would probably only find the initial homepage; subsequent pages are unlikely to be found without an XML sitemap.
XML sitemap example:
<? xml version = "1.0" encoding = "UTF-8"?> <urlset xmlns = "http://www.sitemaps.org/schemas/sitemap/0.9" > <url> <loc> http: // www .example.net /? id=who </ loc> <lastmod> 2009-09-22 </ lastmod> <changefreq> monthly </ changefreq> <priority> 0.8 </ priority> </ url> <url> <loc > http://www.example.net/?id=what </ loc> <lastmod> 2009-09-22 </ lastmod> <changefreq> monthly </ changefreq> <priority>0.5 </ priority> </ url> <url> <loc>http://www.example.net/?id=how </ loc> <lastmod> 2009-09-22 </ lastmod> <changefreq> monthly </ changefreq> <priority> 0.5 </ priority> </ url> </ urlset>
- Biositemap , a protocol for broadcasting and disseminating information about computational biology resources (data, software tools and web-services)
- Contact page
- home page
- Index (search engine)
- Link page
- Search engine optimization
- Sitemaps , an XML standard for URL inclusion
- Web indexing
- Jump up^ Site MapJakob Nielsen’s Usability Alertbox, August 12, 2008
- Jump up^ “Google, Yahoo !, Microsoft Standardize Against Google Sitemap Protocol” . Oreilly . Retrieved 2012-07-24 .
- Jump up^ Joint announcementfrom Google, Yahoo, Bing supporting Sitemaps
- Jump up^ “Submitting Sitemaps” . Google . Retrieved 2012-07-06 .
- Jump up^ Foster, Wes (April 5, 2017). “What is a Sitemap?” . WESFED .