To add to the previous answer:
GM crops are crops whose genomes are altered in order to reinforce their strong qualities, such as resistance to pestilence, ability to nourish, and others, and to rid them of any weakest links. There are lists of foods available in which one of the ingredients had been genetically modified to preserve their freshness, shelf life, consistency, and flavor. Most of these GM ingredients are found in frozen foods, packed snacks (such as tortilla and potato chips), and other products which require specific textures and tastes to appeal a market. Deductively, this shows how potatoes, corn, tomatoes and the likes, are the crops that are mostly GM'd for the purpose of being used for more popular foods as well.
Crop refers to a large number of plants of any given kind that are grown for human use. Crops grown to produce food people and animals, fibres for clothing for other use, raw material for medicines, and ornamental material.
Genetic engineering has been used to produce new varieties of crops that improve the crops in several ways like quality of the final output produced, yield of farming, time required for harvesting, and adaptability to different environment.
For thousands of years people across the world have used breeding methods to produce favourable combinations of genes. These methods have produced most of the economically important varieties of flowers, vegetables, grains, and animals. In the 1970's and 1980's, scientists developed ways to isolate individual genes and reintroduce them into cells or into plants, animals, or other organisms. Such techniques alter the heredity of the cells or organisms.
Hundreds of genetically engineered plants have been developed using such modern methods of genetic engineering. Some examples of genetically modified crops are tomato plants to enable them to produce tomatoes with increased flavour and shelf life; soybean, maize, and cotton plants resistant to herbicides, plants to produce small amounts of a biodegradable plastic and plants to produce material for potential use in medicines.