Ritalin is***a***brand***name***for***methylphenidate, a***central***nervous***system***stimulant***commonly***prescribed***to***treat***attention***deficit***hyperactivity***disorder (ADHD) and***narcolepsy. It***works***by***increasing***levels***of***dopamine***and***norepinephrine***in***the***brain, which***helps***improve***attention, focus, and***impulse***control***in***individuals***with ADHD. Ritalin***is***available***in***immediate-release***and***extended-release***formulations***and***is***usually***taken***orally. It***is***a***controlled***substance***due***to***its***potential***for***abuse***and***dependence. Common***side***effects***include***insomnia, decreased***appetite, and***increased***heart***rate. It***should***be***used***under***medical***supervision.