A hybrid is a type of crossing between two different species or varieties. The term is most often used in reference to the breeding of animals or plants, but it can also be used in reference to the offspring of such a cross.
In animal breeding, a purebred sire and dam are usually mated to produce hybrids. For example, a stallion with desirable traits may be bred to a mare with complementary traits in order to create offspring that inherit the best characteristics of both parents. In plant breeding, crosses between different varieties or species are often made in order to produce hybrids with desired characteristics. For instance, farmers may cross two varieties of corn that have different resistance to pests in order to create a third variety that is resistant to both types of pests.
Hybrids can also occur naturally when members of different species mate and produce offspring. For example, horses and donkeys can mate and produce offspring called mules. Mules are sterile, however, so they cannot reproduce. Similarly, lions and tigers can mate and produce sterile offspring called ligers.