how you find the needle without checking every piece of hay first.
means algorithms and strategies for locating a target within a space of possibilities, trading time, memory, and certainty against each other.
from formalized in computer science through the 1950s-60s alongside AI research, but the core idea is ancient: any systematic way of narrowing down possibilities, from library card catalogs to detective work.
google pagerank — 1998 algorithm ranked web pages by link importance, not keywords
deep blue minimax — 1997 chess engine searched millions of positions to beat kasparov
gps route finding — a-star search plans shortest driving paths in real time daily
dna sequence alignment — blast algorithm searches genetic databases in seconds, not years