Peppermint has attractive, fragrant dark purple/brown serrated leaves and produces little mauve flowers. It is best to remove the flowers as soon as they appear as they will reduce leaf production. It has a strong flavour so use sparingly, great in puddings/chocolate mousse and tea infusions.
Mint grows to 60cm and has an infinite spread - it is an invasive plant. To stop it spreading out of control it is best to plant it in a container and then plant the container into the soil. This will help contain its spread, repot when necessary. It can be kept easily in a pot. It is a hardy herbaceous perennial that dies back each autumn and regrows the following spring, some mulch in autumn will help it through winter.
It is a good companion plant as it repels many insects by it's strong aroma so plant near brassicas. Don't plant two different types of mint near each other as they will cross and both their flavours will become inferior.