Accuracy
From Bulbapedia, the community-driven Pokémon encyclopedia.
Accuracy is an aspect of moves that determine how often they can hit their target. Accuracy currently can be any number between 30% and 100%, usually in multiples of 5.
In the Generation I games, accuracy was technically determined as a fraction of 256, with 255/256 being the highest value it could be (FF in hexadecimal, the highest it can be before rolling over to three digits). Due to this, moves with 100% accuracy (which cannot miss unless a stat-altering move is used) technically have 99.6% accuracy, meaning that once in a great while they will miss for no reason whatsoever. This accuracy problem, which also extended to additional move effects such as paralysis and poison, was resolved in Generation II.
Many moves have an accuracy of "—%"; this either means that they affect no one but the user, affect the partner, or will not miss the target unless they use a move that gives them complete invulnerability for a turn.
Accuracy is raised by 30% if the Pokémon have the ability Compoundeyes.
