Shorts are a type of pants that have short legs. Since they are a type of pants, they must have a crotch piece that connects between the legs, as without this piece the garment would be a skirt instead. Shorts are typically are not very full with fabric, with the exception of culottes. Culottes are shorts that are a cross between shorts and and a skirt, ie shorts full enough to make it hard to see they are not a skirt.
Shorts are typically no longer than knee length. Pants longer than knee length but shorter than full length pants are usually called three-quarter pants instead. Shorts can be very small; as long as the small garment goes around the body and still has a crotch, the garment is still called shorts. The shorts legs can be extremely short or long, and the top of the shorts can go up to the bottom of the ribs or as low as is possible with the shorts legs still being below the top of the garment.