A sitemap is a visual or text map of a site - an index of all pages grouped in sections as they appear on the website. The sitemap is a single file and its presence may have a crucial effect on the popularity of your website, particularly if you have more content. It will make it possible for visitors to browse the web pages and find what they need much faster, that will increase the chance for them to come back to the website or to show it to colleagues and friends. The sitemap is also required for search engines to index your site content better, which means that certain pages will be in the results for specific searches, which will most likely not happen without having a sitemap even if you have the required website content. This is especially valid in case you update some web pages since the sitemap tells the search engines that they must crawl this website again so as to index the new content. Having a sitemap today is essential rather than an optional attribute for any profitable Internet site.