They are food crops that have had their genes altered by inserting a desired gene from another organism (be it a plant or non-plant organism). By doing so, the genetically modified food crop will have the desired feature be it for nutritional purposes or to withstand torment from pests, chemicals or climatic changes. This method is more feasible as compared to plant breeding which is not as quick and reliable.
A common example of such gene donor for food like corn is Bacillus thuringiensis. With this gene, the food crop will be able to form crystal proteins that will prevent the growth of insect larvae (being pest resistant) and thus reducing or eliminating the need of pesticides. to be updated =)
