Crawler

What is a Crawler?
A crawler is an internet program that systematically browses the web to discover and index pages. It is essential for search engines to gather data for their search results. There are specific crawlers for indexing different types of content, such as HTML, images, and videos.

Good vs. Bad Crawlers

• Good Crawlers: Identify themselves, follow directives, and avoid overloading servers. They help by indexing content or auditing websites.
• Bad Crawlers: Add no value, often have malicious intent, ignore directives, and can overload servers or steal data.

Types of Crawlers

1. Constant-crawling bots: Crawl continuously to discover new pages and recrawl old ones (e.g., Googlebot).
2. On-demand bots: Crawl a limited number of pages when requested (e.g., AhrefsSiteAudit bot).

Why is Website Crawling Important?
Crawling is vital for search engines to index and display your content in search results. Regular crawling ensures updated content is indexed, enhancing visibility and traffic. SEO tools also use crawlers to audit websites and identify SEO issues.

How Do Crawlers Work?
Crawlers discover URLs through sitemaps, links, and manual submissions, then follow allowed links. They respect robots.txt rules and nofollow directives. Large websites may have a limited “crawl budget” determined by PageRank, update frequency, and page importance.

Mobile vs. Desktop Crawler Versions
Googlebot has two versions: Desktop and Smartphone. With mobile-first indexing, the Smartphone agent is primarily used. Different versions can be presented to different types of crawlers, identified by their User-Agent string.

Best Practices for a Crawl-Friendly Website

1. Check Your Robots.txt File: Ensure it doesn’t block important pages.
2. Submit Sitemaps: Help crawlers discover all your site’s pages.
3. Use Crawler Directives Wisely: Allow important pages to be crawled.
4. Provide Internal Links: Help crawlers navigate your site.
5. Reduce 4xx Errors and Unnecessary Redirects: Avoid dead ends for crawlers.
6. Use Ahrefs Site Audit: Identify and fix crawlability issues.

FAQs

• Is Crawling and Indexing the Same Thing?
• No. Crawling is discovering web pages, while indexing is analyzing and storing them in the search engine’s database.
• What Are the Most Active Crawlers?
• Googlebot, Bingbot, Yandex Bot, Baidu Spider, and AhrefsBot.
• Do Crawlers Hurt My Website?
• Most do not, but some bad crawlers can harm by consuming bandwidth or stealing data.