Blood behaves not unlike those spilled water droplets, and the speed at which the droplets travel when they strike a surface, known to analysts as a target, affects their shape. This speed, combined with angle and surface characteristics, also determines how far blood droplets skip or bounce after meeting a barrier. Bullet wounds can produce both back and front spatters. Backspatter, or blowback, refers to blood exiting the entrance wound in the direction opposite the impact Investigators dealing with such small drops must rule out other sources of blood spray, such as respiration or pinhole arterial pressure