Understanding the active ingredients in sunscreen is a bit like learning a foreign language that uses a different alphabet. Suffice it to say in short that sunscreens are made up of a combination of two types of ingredients: those that reflect ultraviolet (UV) rays and those that absorb UV rays. Although that might sound simple enough, there are also two types of rays: UVA rays and UVB rays. UVB causes sunburn at the outer layers of skin, but UVA causes sun damage that reach deeper layers of skin. Both UVA and UVB radiation can contribute to the development of skin cancer. Also known as PABA, aminobenzoic acid was one of the first active ingredients in sunscreen. It has been banned in many Europe because it has been shown to cause allergies and clothing discoloration among other things. It is still approved in the US and Australia, but it is more common to see ingredients labeled as PABA-free than to actually contain PABA. Keep in mind that a sunscreen’s Sun Protection Factor (SPF) is a gauge of how well the formula protects the skin from UVB rays. It does not gauge protection from UVA rays.