During your action, you designate an opponent and receive a +1 dodge bonus to Armor Class against attacks from that opponent. You can select a new opponent on any action.

Also, you get a +4 dodge bonus to Armor Class against attacks of opportunity caused when you move out of or within a threatened area.

A condition that makes you lose your Dexterity bonus to Armor Class (if any) also makes you lose dodge bonuses. Dodge bonuses (such as this one and a dwarf's racial bonus on dodge attempts against giants) stack with each other, unlike most types of bonuses.