When it comes to technical SEO, it can be challenging to grasp how everything works. However, we must gain as much knowledge as possible to optimize our websites and reach a larger audience. The web crawler is one tool that plays an important role in search engine optimization.

Crawling thousands of billions of web pages, indexing them, as well as serving them to you is how search engines work. Once you enter a search query into a search engine, web crawlers, known as bots or spiders, crawl thousands, if not millions, of pages in their index, select the most relevant (based on various factors), and end up serving you an answer.

Now that you know how search engines work, let’s dive deep into the procedures that search engines and web crawlers use to understand the web.

What is Search Engine Crawling?

Crawling is the process by which search engine web crawlers (bots or spiders) visit, download, and extract links from a page to discover additional pages.

Pages known to the search engine are crawled regularly to see if there have been any changes to the page’s content since the last time it was crawled. When a search engine detects changes to a page after crawling it, it will update its index to reflect these modifications.

How Does Web Crawling Work?

The Internet is rapidly evolving and growing. All commercial search engine crawlers begin crawling a webpage by downloading its robots.txt file, which contains regulations surrounding which pages search engines should and should not crawl on the site.

Crawlers in search engines use different algorithms and guidelines to determine how frequently a page should be crawled and also how many pages on a site should be indexed. 

Most web crawlers do not and are not intended to crawl a whole publicly available Internet; instead, they choose one page to crawl initially depending on the number of other pages that link to that page, the number of visitors that website receives, and other factors that indicate the page’s possibility of possessing valuable information.

The idea is that a webpage that is referenced by a lot of other webpages and receives a lot of traffic is likely to produce high-quality, comprehensive data, so it’s particularly important that a search engine indexes it – just as a library may keep a plenty copies of a book which gets checked by a lot of people.

What are some web crawler examples?

Every popular search engine has a web crawler, and the larger ones have multiple crawlers with different focuses.

Google, for example, has its main crawler, Googlebot, which includes mobile and desktop crawling. Moreover, Google has several additional bots, including Googlebot Images, Googlebot Videos, Googlebot News, and AdsBot.

Why web crawlers matter for SEO

SEO improves your site’s rankings by making pages accessible and readable to web crawlers. Crawling is the first method search engines find your pages, but regular crawling enables them to showcase changes you make and keep up to date on the freshness of your content. Since crawling extends well beyond the start of your SEO campaign, consider web crawler behavior as a proactive measure to help you appear in search engine results and enhance user experience.


Search engine crawlers are incredible tools for discovering and cataloging website pages. This is a fundamental pillar for your SEO campaign, and an SEO agency can provide your company with a comprehensive campaign to increase traffic, revenue, and SERP rankings.

Brandshark is a creative digital marketing agency, and we are always ready to deliver significant results for our clients. We have vast experience with clients from various industries and they are thrilled with their partnership with us.