As a professional, I often get asked what the difference between an annual and a perennial is. To clear that confusion up, I have decided to clarify it with this post. When talking about annuals and perennials, people are often referring to flowers, but these terms can also be used when talking about herbs.
Annuals: Annuals are flowers and herbs that live out their entire life cycle in one season. This means that the plant flowers/fruits and produces seed before dying in the fall. The next spring, these plants have to be replanted, because they can't survive in our winter hardiness zone here in PA. These plants usually grow as perennials in more mild, tropical climates. Examples of annuals are: Impatiens, Petunias, Pansies, Marigolds, and Nasturtiums.
Biennials: Biennials refer to flowers that grow for one season, then come back the next season and die the third season. These plants flower/fruit, then produce seeds during the first and second year of their lifecycle, then die after that. An example of a common biennial is Snapdragons.
Perennials: This term refers to flowers/herbs that flower/fruit every season, die back in the fall and come back every spring. Perennials don't have to be replanted every year like annuals do. An example of some common perennials are: Gaillardia, Daisies, Rudbeckia, and some species of Salvia.