A heuristic is a replicable method or approach for directing one's attention in learning, discovery, or problem-solving. It is originally derived from the Greek "heurisko" (εὑρίσκω), which means "I find". (A form of the same verb is found in Archimedes' famous exclamation "eureka!4th century AD by Pappus of Alexandria.
The study of heuristics is sometimes called heuristic, but more often called heuristics. Heuristics, in this sense, is treated as a singular, like physics or mathematics.
The mathematician George Pólya popularized heuristics in the mid–20th century, in his book How to Solve It. He learned mathematical proofs as a student but he did not know, nor was he taught, the ways mathematicians arrived at such proofs. How to Solve It is a collection of ideas about heuristics that he taught to mathematics students – ways of looking at problems and formulating solutions.
The word is used adjectivally ("Is it heuristic?") in relation to research or intellectual pursuits. For example, a good theory or idea may be heuristic in that it attempts to find something out or stimulates further investigation. When criticizing theories in the sciences good theories tend to be heuristic.