Single vision lenses
Single vision lenses are worn for reading if you are long sighted and for distance if you are short sighted. These lenses have a single focal power and correct close-up or distance vision.
Multifocal lenses
If you need spectacles to improve close-up and distance vision, one option is to have two pairs of spectacles but this can be both inconvenient and frustrating.
Bifocals are two lenses in one, enabling you to see clearly in the distance and close-up, but they cannot cater for the intermediate distances.
Varifocal (Progressive) lenses avoid the restriction of bifocals. They offer complete vision at all distances and look better cosmetically because they have no dividing lines or segments