DEF

DEF refers to the Defense Points of a monster. If a monster attacks another with an ATK that is greater than the DEF of that monster, the Defense Position monster is destroyed.

If the same situation is reversed, where the ATK is lower than the DEF, both monsters remain on the field, but the owner of the ATK monster loses life points equal to the difference between ATK and DEF.

If ATK and DEF values are the same, neither monster is destroyed, and neither player loses life points.