Unlike annuals and perennials, groundcovers cannot be defined by their life cycle or, for that matter, by any other scientific qualification. Traditionally, the designation "groundcover" has referred to any spreading plant used to cover a specific area of the landscape. There are many shrubs, annuals, perennials and vines that would fit that description - for our purposes, let's narrow our definition down to a low-growing, spreading, evergreen perennial.
Groundcovers have many practical uses in the landscape. If you have a shady spot where turf grass refuses to grow or a hill that washes away bit by bit each time it rains, a groundcover is the perfect solution. Use a groundcover ornamentally to fill cracks in your stone patio, to border your beds or as a more decorative alternative to mulch. Groundcovers make good fillers for container gardens as well.