How does an internet search work? Do they get slower for each new internet page created or are there mecanisms to avoid that?
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A web search engine has a copy of every web page. Each one is given a number.
An index is built. For every word, there is a list of all the numbers of the web pages that have that word. This list is in order.
To search for multiple words, we walk though the index lists of each of them, looking for numbers of web pages that appear in both lists. For example, if one word is on pages 2, 5, and 100, and the second is on 1, 5, and 50, then page 5 is one of our hits. These scans are fast because we can “fast forward” on the index lists and skip lots of comparisons.
Once we have the pages that might answer your query, we have to pick the best ones and show them to you.
When the web gets bigger, the index gets bigger. But searches stay about the same speed because many computers work together on them, and computers keep getting faster and cheaper. Figuring out how to get many computers to work together effectively is hard and fun.
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