When they people want to improve their SEO they should submit their site map to the Google, so that they could get some response from them. There are two different types of sitemaps presents first is the xml sitemap and other is the html sitemap. The basic structures of them are same and they could differ very lightly from each other. When they submit their xml sitemap to the Google they should use the Google webmaster tool. When the people add their sitemap to the Google they could see all their pages could be added in the search engines so that their page rank also could be high when compared to other sites. The other important factor is that they get the link popularity. That they could get links from other sites so that they become more important in the search engines. Is the people have large site, the site map helps to provide quick access to the important pages that could be very useful for the people. When they have site map then they could use the three column layout that could be very useful for them.  For small sites the sitemap could be small and they could have all the information in them.