A sitemap is a visual or text map of a website - a short list of all pages arranged in sections as they show up on the site. The sitemap is a single file and its presence could have a significant effect on the popularity of your site, especially when you have a lot of content. It will enable your visitors to browse the web pages and find what they need way quicker, that will increase the chance for them to return to the site or to share it with colleagues and friends. The sitemap is also needed for search engines to index your site content better, so that some pages will be in the results for certain searches, which may not happen without a sitemap even if you have the required content. This is especially valid when you modify some web pages as the sitemap informs the search engines that they must crawl this website again to index the new content. Having a sitemap these days is essential rather than an optional attribute for every profitable Internet site.