Catnip is a herb that is famous for its effects on cats. It's a member of the mint family (Lamiaceae) and is widely recognised for its ability to induce playful and sometimes euphoric behaviour in cats.  
Catnip is a perennial herb that typically grows to a height of about 2 to 3 feet (60 to 90 centimetres).  It has triangular, grey-green leaves with serrated edges that are covered in fine hairs.  The plant produces spikes of small, tubular flowers that are usually white with lavender or purple spots.
Catnip contains a compound called nepetalactone, which is responsible for its unique effects on cats. When cats come into contact with catnip, either by sniffing, licking, or chewing it, they often exhibit playful, energetic, or even euphoric behaviours.  Common behaviours include rolling, pouncing, purring, and increased activity. However, the response to catnip varies from cat to cat, and not all cats are affected by it.
Catnip has been used in traditional herbal medicine for its potential mild sedative and digestive properties.  It was sometimes made into teas to soothe upset stomachs or alleviate anxiety but Catmint is preferred as more palatable.