Catnip is a hairy plant that is related to mint.
"So, what is catnip to cats? For some, it’s really not much. But for those who find it intoxicating, it is the equivalent to chocolate made from real chocolate or a bottle of the world’s best ranked wine for the connoisseur. It is completely and totally that absolute most precious delight that makes your cat dream pleasant dreams and make nice with the entire family. It is that one moment of absolute bliss amidst an otherwise ordinary day. For cats who respond to catnip, there is little else that can compete with it. In fact, a few informal studies were conducted that proved a cat’s preference to catnip over just about anything. Cats were given choices between catnip and their food, catnip and broiled fish, and even catnip and chicken livers. 93% of the cats involved chose the catnip over everything else. This in itself is a pretty strong testimony straight from the mouths of kitties."