Heuristics is the study of heuristic methods and is used as a synonym as a noun. The word 'heuristic' comes from the Greek, meaning 'discover', and contains several meanings which have expanded with usage into multiple possible meanings depending on context:

1. A rule of thumb or 'common sense' approach used based on experience to achieve a close solution to a problem. The theory is that the set of rules used improves the chances of finding the answer.
2. In engineering, a 'benchmark' approach to a problem used to reduce calculation.
3. In computer science, a formula to achieve an acceptable result.
4. Common usage expresses heuristics as an informal form of good judgment.