What is the difference between annuals and perennials?

Annuals live for just one season and tend to bloom all season long but will die in the same year.  These can be purchased as seeds or seedlings to plant and tend to need less care.  Perennials can also be purchased as seeds or seedlings and live for three or more growing seasons.  Then tend to have shorter bloom periods so to keep constant color from spring to autumn, pair with plants that bloom at different times.