An annual is a plant that germinates, grows quickly, flowers and produces seed in one growing season dying before or during the winter.
A biennial is a flowering plant that takes two years to complete its lifecycle. In the first year the plant grows leaves, stems, and roots but usually does not produce flowers. The plant then goes dormant for the winter before waking up the next year when it then flowers and produces seeds before it dies.
A perennial is a herbaceous plant that lives for more than two years. Perennials go dormant and lose their vegetation in the fall but come back from their rootstock in the spring. There are short-lived perennials that live 3-4 years and long lived ones that live for several decades.