The sunlight that reaches the earth has ultraviolet A and ultraviolet B (UVA and UVB) rays. These ultraviolet rays are the main causes of damage to the skin from the sun. UVA and UVB rays affect the skin's sensitivity to sun exposure in different ways.
Sunscreens that say "broad-spectrum" can protect the skin from both UVA and UVB rays. Sunscreens come in lotions, gels, creams, and ointments.
WebMD Medical Reference from Healthwise