A formula or method for providing a relative measurement of the quality or worthiness of an individual in an artificial intelligence application.

Factors and ways to evaluate individual programs performance in solving the problem. In example of artificial path finder, fitness function ca base on energy spend, energy gain, path length or combination of more than one factor mentioned.

A function that measures the quality of an individual with respect to the given target function, usually as a real value.

A process which evaluates a member of a population and gives it a score or fitness. In most cases the goal is to find an individual with the maximum (or minimum) fitness.

A fitness function is a particular type of objective function that quantifies the optimality of a solution (that is, a chromosome) in a genetic algorithm so that that particular chromosome may be ranked against all the other chromosomes. Optimal chromosomes, or at least chromosomes which are more optimal, are allowed to breed and mix their datasets by any of several techniques, producing a new generation that will (hopefully) be even better.