Googlebot
what is Googlebot?
Googlebot is the crawler used by Google to index its content if it is worth it for the users. This bot has mobile and desktop crawlers, as well as, for crawling news, images and videos. In other words, Googlebot itself has different crawlers for different tasks, and each of them has its user agent.
These crawlers exist to crawl over new pages, discover new content, and send it into processing so that these pages can be indexed. It ensures crawling while considering the rules of robots.txt and page directives.