Genetically modified organisms (GMO) have been one of major discussion topics of consumer and thus researchers. These products have a special importance because they can be applied to any kind of living organism (animal, plant and microorganisms) and because they can affect the public and animal health through consumption of food and feed products. They have received a strong public reaction since they were first developed. Several unions have been developed and lobby activities have been organised to ban GMOs. However, most of these discussions have been run on an unscientific base because of misinformation. As a result of these discussions and uncertainties on the safety of GMOs several countries published legal requirements on environmental release and presence in food and feed chain of GMOs. The aim of this review is to give general information on GMO reality. For this general introduction, the size of their production and trade, informed advantages and potential hazards related to them, legal requirements for GMOs, consumer reactions, and information on detection methods in food and feed are given.