Genetically modified foods (GM foods, or biotech foods) are foods derived from genetically modified organisms (GMOs), such as genetically modified crops or genetically modified fish. GMOs have had specific changes introduced into their DNA by genetic engineering techniques. These techniques are much more precise than mutagenesis (mutation breeding) where an organism is exposed to radiation or chemicals to create a non-specific but stable change. Other techniques by which humans modify food organisms include selective breeding; plant breeding, and animal breeding, and somaclonal variation. Commercial sale of genetically modified foods began in 1994, when Calgene first marketed its Flavr Savr delayed ripening tomato. Typically, genetically modified foods are transgenic plant products: soybean, corn, canola, rice, and cotton seed oil. These may have been engineered for faster growth, resistance to pathogens, production of extra nutrients, or any other beneficial purpose.