SPF (Sun Protection Factor) refers to a rating for the degree of protection a product provides against UVB rays. The higher the SPF number, the more protection from UVB!
UVB (for burning) ??? are energy intense, short waves of ultraviolet light. The intensity of UVB rays vary by season, location and time of day and will usually burn the top layers of your skin.
UVA (for ageing) ??? are less energy intense, long waves of ultraviolet light, meaning they can penetrate deeper into the skin, reaching the dermis. Unprotected exposure can lead to premature skin ageing. Unlike UVB Rays, UVA is present all year round, whatever the season, whatever the weather and can even go through windows!