what is the name of crawlers of the major search engine?
 

what is the name of crawlers of the major search engine and how they work?

Googlebot is Google's web crawling bot (sometimes also called a "spider"). Crawling is the process by which Googlebot discovers new and updated pages to be added to the Google index. We use a huge set of computers to fetch (or "crawl") billions of pages on the web.

"Googlebot" is the bot name of Google Search Engine.