Crawler / SEO Terms Crawler A crawler is an automated software program that systematically browses websites to collect and index information. Crawlers are used by search engines such as Google and Bing to discover web pages and evaluate their content for inclusion in search results. Sometimes called spiders or bots, crawlers help search engines understand what each page is about and how it connects to other content on the web. When a crawler visits a website, it starts with a known page and follows hyperlinks to discover new content. It scans the HTML code, extracts metadata, reads headings and text, and logs the relationships between pages. This data is stored in a search engine’s index and used to determine how and where pages should appear in search rankings. Site owners can use tools like robots.txt and meta directives to control what a crawler is allowed to access and index. Optimising a website for crawler accessibility is a key part of technical SEO. A well-structured site with logical navigation, internal linking, fast load times and a clear sitemap makes it easier for crawlers to index content accurately. Pages that cannot be crawled may not appear in search results, which affects visibility and performance. Errors such as broken links, infinite loops or blocked resources can prevent successful crawling. Monitoring crawler activity through tools like Google Search Console or Screaming Frog helps teams identify problems early and maintain strong search engine visibility.