At 1st level, a monk gains Improved Unarmed Strike as a bonus feat. A monk's attacks may be with fist, elbows, knees, and feet. This means that a monk may make unarmed strikes with his hands full. There is no such thing as an off-hand attack for a monk striking unarmed. A monk may thus apply his full Strength bonus on damage rolls for all his unarmed strikes.
Usually a monk's unarmed strikes deal lethal damage, but he can choose to deal nonlethal damage instead with no penalty on his attack roll. He has the same choice to deal lethal or nonlethal damage while grappling.
A monk's unarmed strike is treated as both a manufactured weapon and a natural weapon for the purpose of spells and effects that enhance or improve either manufactured weapons or natural weapons.
A monk also deals more damage with his unarmed strikes than a normal person would, as shown above on Table: Monk. The unarmed damage values listed on Table: Monk is for Medium monks. A Small monk deals less damage than the amount given there with his unarmed attacks, while a Large monk deals more damage; see Small or Large Monk Unarmed Damage on the table given below.