Sunlight has many types of rays, the most damaging are UV rays, of which there are two predominant types: UVA and UVB.
Unprotected exposure to UVA and UVB damages the DNA in skin cells, producing genetic defects, or mutations, that can lead to skin cancer. UVA rays penetrate deeply into the skin and play a larger role in skin aging, as well as in skin cancer formation (though not as great a role as UVB). There are approximately 500 more UVA rays in sunlight than UVB rays, so it is important to protect against both by wearing a broad-spectrum sunscreen and staying out of the sun where possible.
