Information Retrieval : Finding a needle in a haystack

Information retrieval (IR) is the science and practice of trying to show people the document they would want to see next, if they had total knowledge and hindsight.

One way to grasp the wide scope of IR field is to dig into the "needle in a haystack" metaphor. Here's Matthew Koll's "Finding a needle in a haystack" metaphor for it.

Searching is like finding a needle in a haystack, but not all searches are the same.

• a known needle in a known haystack;


• a known needle in an unknown haystack;


• an unknown needle in an unknown haystack;


• any needle in a haystack;


• the sharpest needle in a haystack;


• most of the sharpest needles in a haystack;


• all the needles in a haystack;


• affirmation of no needles in the haystack;


• thinks like needles in any haystack;


• let me know whenever a new needle shows up;


• where are the haystacks?;


• needles, haystacks – whatever.

I may add, as a matter of fact (because it does happend a lot) "wrong query for a needle in a haystack, and finding something anyway". That's is what is called serendipity...
(Via Olivier Ertzscheid)