In the world of search engine optimization (SEO), a crawler (Finnish: Indeksointirobotti) refers to a program used by search engines to traverse the internet, gather, and index information. For example, to make a website appear in Google search results, a crawler must first visit the site and index it.
Crawlers use the hyperlinks found on web pages to navigate from one site to another. Upon reaching a site, the crawler examines the site’s content and embedded links before following the links to exit the site. The crawler continues to follow links until it has indexed information from every page linked to another site. Essentially, it “crawls the web,” hence the term “crawl the web.”
Why are crawlers important in search engine optimization?
First and foremost, if you want your site to appear in search engines at all, search engine crawlers must first discover and index your page. Without indexing, your site won’t be found in search engines, even if you search for it by its exact name.
Search engine crawlers don’t browse the entire internet but rather rank websites based on criteria such as traffic or backlinks. Based on this ranking, a crawler decides which pages to visit and how often to update the indexing of desired pages.
You can influence the ranking given by crawlers by ensuring your website is crawler-friendly. Crawlers prefer websites that are easy to crawl, meaning they are easy to access and navigate. The fewer clicks required to access important content, the more pleasant the experience for both crawlers and human users. Crawlers also use sitemaps provided by websites for navigation.
Secondly, crawlers follow inbound, outbound, and internal links on a page. To allow a crawler to follow internal links, the link structure on your page should be well-organized. External links leading away from your site indicate to the crawler that other sources have been used, which can increase the site’s credibility. Crawlers also look for keywords on pages to determine how your site should be listed in search engines. Additionally, they monitor page content for duplicated content to ensure the uniqueness of the page’s content.