What Hillbilly just explained. Also, understand that a bow may have both at the same time, where around the handle area it is deflexed (bending towards you) and then about mid-limb out to the tips it reflexes, and bends away from you. Or even vice-versa, as in the build-a-long that Jackcrafty is doing on native american plains bows that reflex in the handle and then deflex out towards the tips.
~~Papa Matt