Heuristic
Last Updated: July 29, 2026 | By Mihail Sebastian | AI Dictionary
A practical shortcut or rule of thumb that finds a good-enough solution fast when computing the exact answer would take too long or cost too much.
What is a Heuristic?
A heuristic is a problem-solving shortcut: a rule of thumb that finds a good-enough answer fast when computing the exact answer would take too long or cost too much.
Psychologists use the same word for the mental shortcuts people take. In AI it means shortcuts deliberately built into programs, and it is not the opposite of an algorithm: heuristic rules run inside algorithms, guiding choices when exhaustive search is out of reach.
How Heuristics Work
Many problems explode combinatorially. Finding the truly shortest tour through 50 cities means checking more orderings than there are atoms in the universe; a heuristic such as “always visit the nearest unvisited city” produces a decent tour in a fraction of a second. The trade is explicit: speed in exchange for the guarantee of the best answer.
Search is where heuristics earn their keep. The A* pathfinding algorithm uses an estimate of the remaining distance to the goal to decide which paths to explore first, so it examines promising routes instead of every route.
Game-playing programs work the same way. A chess engine cannot search to checkmate from most positions, so it scores positions with heuristics like material count and king safety, a contest examined in Chess Showdown: Grandmasters vs. AI Algorithms.
Example of a Heuristic
A navigation app asked for a route across a city cannot afford to explore the entire road network. It uses the straight-line distance to the destination as its heuristic.
At each step, the app extends the candidate route whose driven-distance-so-far plus straight-line-remainder looks smallest. Roads heading toward the destination get explored first; roads heading away are set aside unless the promising ones dead-end.
The straight-line estimate is wrong in detail, since no road is perfectly straight. It is right in spirit, which is all a heuristic needs to be: the app returns a good route in milliseconds instead of an optimal one next week.
Related AI terms: Algorithm · Optimization · Fuzzy Logic · Expert System
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Mihail Sebastian — Writes about AI governance, regulation, and the technology behind them. Placeholder bio — replace with a real credential line. About