LSD, or lysergic acid diethylamide, is a powerful hallucinogenic drug that alters perception, mood, and cognitive processes. It was first synthesized in 1938 by Albert Hofmann, a Swiss chemist, and is known for its ability to induce vivid visual and auditory hallucinations. LSD is typically taken in small doses, often on blotter paper, and its effects can last up to 12 hours. The drug works primarily by interacting with serotonin receptors in the brain, leading to changes in sensory perception and thought patterns. While some users report profound spiritual experiences, LSD can also cause anxiety and confusion. It is classified as a Schedule I substance in many countries, indicating a high potential for abuse and no accepted medical use.