An English word combination of the terms web and to crawl. Web crawlers are programs that make it possible to find and index websites using bots.


Search engines need and use web crawlers to index domains, list URLs and evaluate website content, but also to delete websites that no longer exist. Web crawlers move automatically and independently within the internet from URL to URL. Web crawlers are bound to an index by which the crawler then adds the websites to the index according to previously defined rules, so that they are listed on the search engine's results pages for certain search entries (see also ranking).