The document discusses the hallucinogenic drug lysergic acid diethylamide (LSD). LSD is a potent hallucinogen that acts as an agonist on serotonin receptors in the brain, triggering effects like altered mental states, delusions, and detachment from reality. It is semi-synthetic, derived from ergot fungus found on grains, with an added synthetic chemical. LSD's chemical structure allows it to mimic the neurotransmitter serotonin in the brain.