It is used to make choices about the chance of an event that is under doubt. It's a group of heuristics who rule judgment defined as "judgmental shortcuts that generally help get us where we need to go often sending us off course". Heuristics use effort-lessening and simple ideas in decision-making.
Diagrams
Originated from/Coined by
Amos Tversky and Daniel Kahneman
Further Reading/ References
https://en.wikipedia.org/wiki/Representativeness_heuristic