Why do cats like catnip?
Catnip contains a chemical called nepetalactone that has an effect on the brain that gives the cat a high. Not all cats are affected.
Not all cats are attracted to catnip, a plant that looks like mint. Cats like catnip for the high it gives. This is probably similar to the kinds of high people get when using recreational drugs. It is not clear if cats can become addicted. It is said that they can. But I have never read about a drug addict cat. Have you?
It provokes certain behavior, such as sniffing it, chewing it and rubbing against it. After these behaviors the cat can lie and looked spaced out.
"Trips" last no more than one hour and it takes about a hour for cats to come down from the effects of the drug.
Catnip can act as a sedative for a cat when taken internally. Another drug Matatabi has a similar effect. It is found in Asia.
Read more about catnip.