"As a Web designer and HTML builder, one of the first places I visit on a Web site is the site map. The site map shows an entire overview of the structure of the site, and more importantly, indicates how much effort was put into usability testing during the site's construction.
"27 percent of users turn to site maps when asked to learn about a site's structure. If your site map is poorly designed, you may lose 27 percent of your Web visitors. That could translate into millions of dollars of missed sales for an e-commerce site, or a massive amount of missed leads for a service company."
(A Site Map is a guide to a web site used by visitors. A Sitemap is a file used by search engines to index entries on a site. )