Combat in my D&D game is resolved upon a hex map. Each hex on the map has a diameter of 5 ft. Combatants occupying a given hex 'hold' that area against all others. A combatant cannot enter a hex occupied by an enemy, but an enemy can be forced through attack and other means to surrender the hex and give ground.

All hexes immediately adjacent to a combatant's hex are subject to attack. Therefore, there is a larger circle over which a combatant can affect enemies. This is called melee.

All movement in combat is measured against a combatants ability to move from one hex to another. Details about this can be obtained in the rules for Movement in Combat. It normally requires 1 action point (AP) to move from one combat hex to another.

Naval hexes, for determining the movement of ships on the water, have a diameter of 20 ft.

See Combat