Worldwide, there are hundreds of different chicken breeds. The American Poultry Association recognizes 65 different breeds of chicken. This list does not include the most populous breed of chicken, the Cobb 500. The Cobb 500 is the breed of chicken used by many commercial chicken meat producers.
The breeds of chicken used by commercial egg-producers are also not on the American Poultry Association's list. Some breeds have been selected for excellent egg production, and others have been selected for excellent meat production. The commercial strains of chicken are the extremes of these two types. In more natural farm settings, some breeds have been selected to produce both eggs and meat.