Besides protecting from overexposure to sunlight, sunscreens help to prevent other problems related to sun exposure, like aging skin and precancerous growths. Classified as drugs by the United States Food and Drug Administration, sunscreens come in forms such as ointments, creams, gels, lotions, and sprays.
Higher numbers indicate more protection.
As a rule of thumb, you always should use a sunscreen with an SPF of at least 15. Not total protection Remember that sunscreen does not provide total protection. When using an SPF 15 and applying it correctly, you will get the equivalent of 1 minute of burning UV rays for every 15 minutes spent in the sun. So, eight hours in the sun wearing SPF 15 sunscreen is the same as spending 32 minutes unprotected. Reflective surfaces like water, snow and sand can cause exposure to more UV rays.