GMO stands for genetically modified organism, which is a plant or animal that has been modified on the genetic level to include genetic material from organisms that would not mix in nature. This is different than cross breeding and grafting, which are techniques that involve closely related species. Biotechnology companies tout the benefits of GMO crops and livestock, but some scientists have significant concerns about the future ramifications of this technology. When the USDA National Organic Program standards were being written, public comments were overwhelmingly against the allowance of GMOs. The USDA took note and the standards strictly prohibit the use of GMO crops and livestock in organic production. So when you purchase organic products, you know that this new and questionable technology was not used at any stage of production.