Crawler

A crawler is an automated bot used by search engines to discover, scan, and index web content across the internet.

Also known as a spider or bot, a crawler systematically visits web pages by following links. Search engines like Google, Bing, and others use crawlers to gather information about websites, update search indexes, and determine how pages should rank in search results.

Why Crawlers Matter in SEO:

• Enable Indexing – Without crawler access, your content won’t appear in search results.
• Discover New Content – Crawlers help search engines find new or updated pages.
• Evaluate Site Health – Crawlers assess structure, internal links, errors, and speed.
• Trigger Ranking Updates – Crawlers re-visit pages to keep rankings fresh and accurate.

How Crawlers Work:

1. Start with a Seed List – A set of known URLs.
2. Follow Internal & External Links – To discover new pages.
3. Fetch and Parse HTML – To read content and metadata.
4. Index Content – Based on what they find.
5. Schedule Re-crawls – Based on frequency, value, or change.

Types of Crawlers:

• Search Engine Crawlers – Googlebot, Bingbot, Yandexbot, etc.
• SEO Tools Crawlers – AhrefsBot, Screaming Frog, SEMrushBot.
• Malicious Crawlers – Bots that scrape or overload servers (to be blocked).

Best Practices for Managing Crawlers:

• Use robots.txt to control what gets crawled.
• Submit sitemaps to guide crawlers.
• Avoid blocking essential content with JavaScript.
• Fix crawl errors in Google Search Console.
• Use noindex tags and canonical URLs strategically.

Example:

When Googlebot visits your homepage, follows links to blog articles, and adds them to Google’s index—that’s crawling in action.