What is the difference between HTML sitemaps and XML sitemaps?
HTML sitemaps appear as a webpage, and are human readable. XML sitemaps are machine readable, making a website more accessible to web robots, such as Googlebot (see also Robots exclusion standard). For visuals, check out my quick and dirty webpage:
I did some work trying to bridge sitemaps with mindmaps, only to discover that they are not really compatible. Websites contain recursive linkages; whereas, mindmaps are strictly hierarchical. For details, see: