Crawling in SEO refers to the process where search engines discover and index content on your website. Search engine bots, or crawlers, visit your pages to analyze their content. You should ensure your website is accessible for crawlers by using a proper site structure. You must create a sitemap to guide crawlers to all important pages. A well-optimized robots.txt file helps control what crawlers can and cannot access. Crawling allows search engines to understand your site's relevance for specific search queries. You should regularly monitor crawling issues to ensure all your important pages are indexed properly.