The vast majority of processed foods in the US contain genetically modified organisms (GMOs), whose DNA has been manipulated in a laboratory using genetic engineering. GMO-free products have no genetically engineered ingredients. Certified organic products must be GMO-free. The non-GMO claim is unregulated, but some products are verified by a third party, like the Non-GMO Project. The Ferry Plaza Farmers Market prohibits the sale of products known to contain GMOs.