Finding information by crawling

The web is like an ever-growing library with billions of books and no central filing system. We use software known as web crawlers to discover publicly available webpages. Crawlers look at webpages and follow links on those pages, much like you would if you were browsing content on the web. They go from link to link and bring data about those webpages back to Google’s servers.

How Google Search organizes information (https://www.google.com/search/howsearchworks/crawling-indexing/)