A Taser is an electro-shock weapon that uses electric current to temporarily stun its target by overloading the sensory or stimulus nerves. This causes the muscles to contract sharply, and spasm as the taser takes effect on its intended target. It can also cause momentary paralysis upon contact with the taser probes. When the dinosaurs were still being assembled into the park on Isla Nublar, management ordered a variety of nonlethal control measures, including Taser guns to help contain the dinosaurs. Henry Wu lamented to John Hammond that all of these controls were to slow to adequately contain the animals.
Jurassic Park by Michael Crichton page 122,130 (First Edition, Thirty Fourth printing)