A sitemap is a file that lists all the pages of a website, helping search engines like Google understand its structure. It serves as a roadmap, guiding crawlers to discover and index the site's content more efficiently. Sitemaps can be in XML format for search engines or in HTML format for users. Creating a sitemap is essential for improving a website's visibility in search results. It ensures that all important pages are included, making it easier for users to navigate. Regularly updating the sitemap can also reflect any changes or additions to the website's content.