The different types of skin:

Phototype I   : Skin that always turns red and never tans.
Phototype II  : Skin that always turns red and sometimes tans.
Phototype III : Skin that sometimes turns red and always tans.
Phototype IV : Skin that never turns red and always tans.
Phototype V  : Skin that darkens slightly.
Phototype VI : Skin that darkens and does not burn.