The normal eye can focus light on the retina to create a sharp image. This condition is known as emmetropia.
Any state other than emmetropia is called ametropia, and results in a refractive error.
The nearsighted eye is too long and light is focused in front of the retina. This condition is called myopia
The farsighted eye is too short and light is focused behind the retina. This condition is called hyperopia.