A web crawler (sometimes referred to as a spider) is an Internet bot that automatically scans data throughout the Web to create an index of data. Search engines like Google or Bing use crawlers. With the help of web crawlers, relevant results can be presented after user searches.

How do crawlers work?

Basically, a crawler is like an online librarian that indexes web pages, updates web information, and evaluates the quality of the content on the site. These crawlers crawl the web like spiders and act as automatic indexers or web robots. This process is also known as web crawling. The most famous web crawler is Googlebot.

The crawler usually starts its work by visiting a list of websites it has visited before. During these visits, it also searches for other related websites worth checking. This allows the crawler to discover new pages or URLs, update changes to existing pages, etc. When a web crawler visits a particular page, it crawls the entire content of the page and then transfers it to its database. Once the data is collected, the words on the page are added to the search engine’s index. You can think of an index as a huge database of words. However, once a website is indexed, the crawlers don’t stop completely. From time to time, they check to see if changes have been made to the website. If something new appears, the index that was created is also updated.

Nowadays, there are so many websites and so many newly created, updated pages every minute of every day that you can imagine the huge amount of work that these crawlers perform. For this reason, search engines have set certain guidelines for the content to be crawled, the order of crawling and the frequency of crawling, etc. For example, a web page that is updated regularly may be crawled more frequently than a page that changes infrequently. All these rules are designed to help streamline the process. Each search engine has its own crawlers that can be used to update website data. It must be said that crawlers play an important role in the internet age. Without web crawlers, it is extremely difficult to find the desired information in such a huge ocean of information.