Website owners should understand that there are two types of sitemaps, and each serve a very different purpose.
An HTML Sitemap is generally a graphical/text representation of the information architecture of your website. It is used to facilitate the navigation process for users of your website. Although sometimes a "site index" (pages listed A-Z) can be useful a sitemap generally provides a better user experience and faster navigation. HTML Sitemaps are always produced to enhance the human user interaction with your website, they serve little purpose for search engines.
An example of an HTML sitemap is the one that we have on this website
XML Sitemaps are mainly used to enhance the indexing process of your website or application. The Sitemap "protocol" in use by major search engines allows them to improve there indexing process and avoid frivolous re-indexing of static content. If your website has some dynamic content then the XML standard allows your new content to be indexed quicker with less load on your server, leading to more hits and lower bandwidth costs.
Google has taken this one step further by allowing webamsters to view the results of the indexing process by logging into there "Webmaster Central", further expanding the usefullness of having an XML Sitemap.
Apart from the previously explained difference in use for each type of sitemap there are some other fundamental differences:
- HTML Sitemaps are for humans to navigate to different areas of your website.
- XML sitemaps are for search engine robots to index all of the parts of your webitste that you want indexed.
- HTML Sitemaps are for really only use the "Title" tag to show the name of the page and not much else.
- XML Sitemaps can contain lots of other information such as "last modified date" to enhance the indexing process for your website. To see what information can be included please look that the sitemaps protocol page.
Having an XML Sitemap for your website will not guarantee that your webpages will be indexed in search engines nor will it necessarily influence the ranking of your pages in search engines. Search engines use XML sitemaps as a supplement to there normal web-crawling activities. Submitting your sitemap to a search engine will facilitate the crawling process but it won't fix bad information architecture nor will it help with poor design or bad pselling :).
In short having an XML Sitemap is not a panacea for bad design, editing or content, BUT in a competitive webmastering world it can make the small difference between first and last.
