Lysergic acid diethylamide, commonly known as LSD, 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 derived from ergot, a fungus that grows on rye. LSD is known for its ability to induce vivid visual and auditory hallucinations, as well as profound changes in thought patterns. LSD is typically ingested in small doses, often on blotter paper or in liquid form. The effects can last up to 12 hours, leading to experiences often referred to as a "trip." While some users report positive experiences, others may encounter anxiety or paranoia, known as a "bad trip." Due to its potent effects and potential for misuse, LSD is classified as a Schedule I controlled substance in many countries.