If you do not have an XML sitemap, search engines will eventually find most of your website's popular content on their own, over time.
However, including an XML sitemap on your website will help search engines to index your website faster and more thoroughly... and may improve the search engine ranking of your webpages.
Fortunately, Google, Yahoo, MSN, and many other search engines now use the same sitemap protocol – which means that you only need to upload and update a single sitemap.
Sitemaps are written with XML tags. Good news: you don't need to learn how to do XML programming since many sitemap generators are freely available. If you prefer utilities that come with technical support, fee-based XML site map generators are also offered.
Google lists several sitemap generator options at: http://code.google.com/sm_thirdparty.html
