Annuals by definition are plants whose life cycle lasts only one year, from seed to blooms to seed. Removing the flowers as they fade prolongs the blooming cycle, but if left to produce seeds, many annuals will readily reseed themselves. Annuals are an excellent way to create a great splash of summer color in the garden, or for long blooming annual baskets.
Biennials are plants that usually only live two years, normally producing flowers and seed the second year.
Perennials are non-woody plants which grow and live for more than two years. Perennials usually produce one flower crop each year, lasting anywhere from a week to a month or longer. Although they live on longer, many perennials lose their vigor after 3-4 years, and should be replaced. Most perennial plants may be divided to produce new plants, or they may be grown from seeds or cuttings.
Bare root plants are plants offered for sale which have had all of the soil removed from their roots.
Bedding plants are plants (mainly annuals), nursery grown and suitable for growing in beds.
(http://www.thegardenhelper.com/planting.html)
