Perennials return for many years. In contrast, annuals don't grow back after completing their life cycle. These plants complete their life cycle in one season (they germinate, flower, produce seed and die). Some annual plants grow back from dropped seed, but typically you must replace them annually (a little word trick to distinguish them from perennials). The list of annuals is long, but some examples include geraniums, impatiens, zinnias, marigolds, petunias and pansies.