A mule is the child of a male donkey (aka jackass) and a female horse (aka mare). If a female donkey (aka jenny) and a male horse (aka stallion) have a baby that child is a hinny. A mule being the cross between a horse and a donkey has the large head and long ears and the body of a horse, and an asslike tail. A mule is smarter than a horse because a horse may overeat and may become ill from over eating but a mule will not. Mules are almost always infertile due to differing numbers of chromosomes between the horse and donkey.
Some mules are very large and are strong and durable. Mules can carry more than the horse or the donkey and have often been used to carry packs. For the past three thousand years mules have been essential in transport. From ancient times til the invention of the steam engine and building of railroads. Mules can be ridden but were mostly used in mule teams or mule trains to pull wheeled vehicles in both peace and war times.
twenty mule teams of Death valley California hauled two wagons loaded with borax plus a water wagon. The weight of these wagons was over twenty seven tons.
Here in Southern Illinois we have a rather famous celebration of the mule. For the past 100 years Enfield has celebrated the mule in mule days.