How do search engines work?

You ask: How search engine find thing?

When Caveman ask search engine, it no run out and read whole internet — internet too big, would take moons. Real work done before Caveman even ask. Search tribe send robot scouts, crawlers, that walk web day and night, follow every link like trail between camps, copy every page they find. Then engine build giant index, like memory — biggest search tribe's index hold hundreds of billions of pages — for each word, list of every page holding that word. Caveman type "mammoth stew" — engine just look up two lists, find pages on both. Then hard part: which page first? Engine rank by many signs — words match good, page fresh, and big one: many other pages point at it, like whole tribe point at best hunter. Caveman get answer in eye-blink because answer was pre-chewed. Cave wisdom: search engine no search web when asked. It search map it drew before.