Food that has been genetically modified means that its DNA structure has been changed. DNA is the basic blueprint of all living things, and by altering it, its quality and characteristics are also changed. For years, humans have been purposely manipulating the evolution of organisms. Farmers use selective breeding to improve the livestock and crops so that cows can produce more milk, hens will lay more eggs and disease-resistant plants will produce more. Genetically Modified Organisms or "GMO's" are plants or animals that have been created by altering the genetic material through gene splicing of genetic engineering. Genetic engineering, however targets manipulations in an unprecedented way. "Transgenic plants and animals are generated with characteristics that cannot be obtained using traditional breeding. Unlike organisms generated by selective breeding, transgenic organisms contain genes from other species. Genetic engineering techniques are used to generate recumbent DNA which contains sequences from different organisms. This DNA then becomes incorporated into a host so that it can be passed to subsequent generations" (Rediscovering Biology www.learner.org.) Such techniques have become commonplace. For example, bacteria produce human insulin and hepatitis vaccines, while some crops can be altered to resist herbicides and insects. Although the economy warrants the process, genetically modifying bacteria, plants and animals comes with its own set of risks. Modifying one segment of DNA does not produce a single result, but one that causes a spiraling of various unwanted consequences.