Hitbox

A hitbox is an invisible shape commonly used in video games for real-time collision detection.

Melee weapon hitbox
In DDO, this term is often used to describe the area where an enemy must be in order for your attack to hit it. It's mainly a combination of two factors:
 * Reach (how far can the enemy be)
 * Facing (do you have to be facing the enemy directly or can it be on your left / right, or even behind you)

In general, the hitbox matches your animation. For example, if your character makes a wide sweeping attack, it can also connect to enemies on your left and right. If the animation is a forward thrust, it can have a slightly longer reach, etc.

Some information about hitboxes:
 * Different weapons have different hitboxes. For example, two-handed weapons have larger reach.
 * Various attacks in an attack sequence can have different hitbox.
 * Special attacks, such as Cleave, can have different (often larger) hitbox.
 * Your attacks while moving can have a different hitbox than when stationary.

See also:

Enemy hitbox
Another meaning of a hitbox is how close to an enemy do you have to be in order to hit. Some large enemies, for example dragons, have a rather big hitbox, i.e. your character may stand quite far from the enemy and your melee attacks still connect.

Being prone does not move your enemy's hitbox. When you trip a tall enemy, for example an earth elemental, the bulk of its body appears to be few steps away. However, its hitbox actually stays in the small area around its feet.