Artificial selection is the process of changing the characteristics of animals by artificial means. It was originally defined by Charles Darwin in contrast to the process of natural selection, in which the differential reproduction of organisms with certain traits is attributed to improved survival and reproductive ability in the natural habitat of the organism. For example, animal breeders are often able to change the characteristics of domestic animals by selecting for reproduction those individuals with the most desirable qualities such as speed in racehorses, milk production in cows, trail scenting in dogs. Another example is the crossing of white corn, or field corn, with yellow corn, or sweet corn and creating a new type of corn for human consumption called Peaches and Cream corn. When the husk is pulled back you can see an even mix between the white and yellow corn.
Artificial selection is when a human determines two organisms to mate and tries to predict the results with regard to one trait. For instance, let's say you want a fast race horse. You go out and choose a male and female horse that are both very fast and have won races. Your hope is that the baby horse will be faster than either of the parents. If you get this result, you have done artificial selection or selective breeding.