Lysergic acid diethylamide (LSD) is a powerful hallucinogenic drug that alters perception, mood, and cognitive processes. It is derived from ergot, a fungus that grows on rye and other grains. 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 commonly referred to as a "trip." While it has been studied for potential therapeutic uses, LSD remains a controlled substance in many countries due to its unpredictable effects and potential for misuse.