Heirloom and heritage foods are derived from rare and endangered breeds of livestock and crops. The term heirloom refers to crop varieties, while the term heritage refers to animal breeds. According to Animal Welfare Association (AWA), "generally speaking, heirloom crop varieties have been in existence for a minimum of 50 years. [Also termed] farmers' varieties or traditional varieties, [heirlooms are] unique plant varieties, genetically distinct from the commercial varieties popularized by industrial agriculture, [and] have been developed by farmers through years of cultivation, selection and seed saving, and have been passed down for generations." No production standards or specific farming practices, such as pesticide or fertilizer use, are required by law for these varieties. However, heirloom farmers tend to use sustainable production methods. Not only does the heirloom/heritage interest in conserving genetic diversity coincide well with other preservation efforts, sustainable farming helps to maintain heritage and heirloom product quality and reputation. There is no independent third party verification for this claim.