What a search really looks in
You search, and results appear in under a second. A search engine is a program that finds pages. It did not read the whole internet just now.
- Pages, out on the internet.
- An engine visits them and writes an index: which words are on which page.
- A search reads the index only.
Search is fast because it reads a list built earlier.
To visit a page is to read it. The engine visits pages ahead of time. It writes down the words on each page. A search then looks in that list.
Rule: A search reads an index built earlier. It lists only pages the engine has visited.
A page the engine has not visited cannot appear. A page that changed may still be listed under its old words.
Watch out!
The top result is not always true. The engine ranked that page high, meaning near the top. The engine did not check that the page is true.
Find the word that finds nothing until page 4 is visited.
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