Poultry exhibitions started in America in 1849. Interest in these shows grew and numerous breeds and varieties were and continue to be developed, leading to the large number of varieties now in existence. There are approximately 175 varieties of chickens grouped into 12 classes and approximately 60 breeds. A class is a group of breeds originating in the same geographical area. Breed means a group which possesses a given set of physical features, such as body shape, skin color, carriage or station, and number of toes.
Variety is a category of breed and is based on feather color, comb, or presence of a beard and muff.
Thus, the Plymouth Rock may be Barred, White, Buff, or one of several other colors. The Rhode Island Red may have either a single or rose comb. In each case, the body shape and physical features should be identical. Breed and variety tell little about the qualities of good producing stock. Strain, however, does.