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Sitemaps are XML-files containing structured data about the pages of the website. They are helpers for search-engines to discover all relevant pages and content on a website. If you are using a framework such as Laravel you can create these on the fly or whenever you publish or update your content. It's heavily reliant on PHP Spider, a crawler package for PHP. The sitemap crawler crawler uses some regex to identify the most interesting parts of the site. More detail can be found on the GitHub repo for Laravel-Sitemaps.