Sitemaps are not something very big. They have always been a slice of best Web design practices. But with the acceptance of sitemaps by search engines, now they have become even more essential. Yet, it is essential to make a clarification that if you are involved in sitemaps mostly from a SEO point of view, you can’t go on with the conventional sitemap only. Currently Yahoo! and MSN still keep to the typical html format. But, Google Sitemaps uses a special (XML-Extended Markup Language) format that is not the same as the ordinary html sitemap for human visitors.
One may ask why two sitemaps are needed. The answer is clear – one is for humans, the extra is for spiders. For now mostly it’s about Googlebot, but it is practical to assume that other crawlers will join the party very shortly. According to that, it is essential to clarify that having two sitemaps is not considered as duplicate content. In “Introduction to Sitemaps”, Google clearly says that sitemap using will by no means lead to penalty for your site.
Sitemaps also help in categorizing your site content. Well, search engines are by no means held responsible to classify a page. As belonging to a particular classification or as matching a specific keyword only because you have told them so isn’t reasonable either.