Hello,
All sites have to have at least two kinds of sitemap: one for the visitors and another for search engines.
Both are inportant, but the search engine sitemap is the most important.
One of my sites has a large database and has around 300 000 dinamically generated pages.
I designed text based navigation to let search engines find and index all the pages.
Google has indexed around 3500 pages that time.
After I've read googles advices about sitemaps, and realized, that the sitemaps are like news feeds. As soon new link, title available, google starts to crawl it as soon as possible.
So I've changed my dynamic sitemap to contain all the dynamic pages of my site.
Three things happened:
- the bandwith usage increased thanks to googlebot
- google indexed 20 000 extra pages in couple of weeks
- My visitor traffic increased because of the large aount of indexed pages
Conclusion:
Search engine sitemaps are essential
SEO tools, search engines discover and index new pages faster with sitemaps and you can get more visitors.
Webmasters! Search engine sitemap is important! Take it serious!