Peppermint is a (usually) sterile hybrid mint, a cross between watermint and spearmint.
Being sterile, it spreads by rooting.
Peppermint has a high menthol content, and is often used as a flavouring in tea, ice cream, confectionery, chewing gum, and toothpaste.
The oil also contains menthone and menthyl esters.
Peppermint generally thrives in shade and expands quickly by underground rhizomes.
If you choose to grow peppermint, it is advisable to plant it in a container, otherwise it can rapidly take over a whole garden.