An
evaluation function is used to heuristically determine the relative value of a position,
i.e. the chances of winning.
If we could see to the end of the game in every line,
the evaluation would only have values of -1 (loss), 0 (draw), and 1 (win).
In practice, however, we do not know the exact value of a position,
so we must make an approximation.
Beginning chess players learn to do this starting with the value of the pieces themselves.
Computer evaluation functions also use the value of the material as the most significant aspect
and then add other considerations.
