Xanax (alprazolam) is a prescription drug in the benzodiazepine family, used mainly to treat anxiety disorders, panic disorders, and insomnia. It acts by increasing the activity of GABA, a neurotransmitter that calms the nervous system, producing a sense of relaxation and decreased stress. Xanax is quick-acting, so it is useful for sudden attacks of anxiety, but it also has the potential for dependence and withdrawal symptoms if abused.