Any website developed has to focus on the fact that the website has content which appeals to the visitors and is easily indexed by the search engine robots.
For that, the search engines have to be informed about the unique URLs of each website. As the website can rank in the search engines only after it has got indexed. Hence, a sitemap is a file which has got a complete list of URLs of your website.
An XML Sitemap is an XML file that lists URLs for a site along with additional metadata about each URL (when it was last updated, how often it usually changes, and how important it is, relative to other URLs in the site) so that search engines can more intelligently crawl the site.
Google mentions on its webmaster blog : http://www.google.com/support/webmasters/bin/answer.py?hl=en&answer=156184
Sitemaps are particularly helpful if:
- Your site has dynamic content.
- Your site has pages that aren't easily discovered by Googlebot during the crawl process—for example, pages featuring rich AJAX or images.
- Your site is new and has few links to it. (Googlebot crawls the web by following links from one page to another, so if your site isn't well linked, it may be hard for us to discover it.)
- Your site has a large archive of content pages that are not well linked to each other, or are not linked at all.
Google doesn't guarantee that we'll crawl or index all of your URLs. However, we use the data in your Sitemap to learn about your site's structure, which will allow us to improve our crawler schedule and do a better job crawling your site in the future. In most cases, webmasters will benefit from Sitemap submission, and in no case will you be penalized for it.
Google adheres to Sitemap Protocol 0.9 as defined by sitemaps.org. Sitemaps created for Google using Sitemap Protocol 0.9 are therefore compatible with other search engines that adopt the standards of sitemaps.org.
In order to create XML sitemaps you need not learn XML. There are many reliable sites which offer this service for free or for a small amount if the site has got more than 500 URLs.
Once you have created a sitemap for your website it has to be submitted in the Google webmaster tools to inform Google about it by adding the right path for the file.An XML sitemap has to be saved in the root directory of the server only.
This ensures that when the Google bot comes to read the content of your website to your server, the complete list of URLs is available on a single file which makes the search engine spiders to easily index the site.
Hence, the presence of the XML sitemap helps to ensure that the search engine bots discover the URLs, they are crawled, indexed and only after that as a result there is any probability for getting ranked in the search engines for targeted keywords.
Of course just the presence of the XML sitemap is not enough for getting ranked, there are many other of-page and on-page factors which finally determine the rankings for any website.
We suggest that if you have a very huge site with 1000+ URLs, then please submit the most important URLs for which the indexing is targeted and the other deeper links will be soon found by the bot in due course of time.
The Video Resources For XML Sitemaps By Google are available on http://services.google.com/breeze/webmasters/googleforwebmasters/