SPF is a measure to identify the ability of sunscreens to protect skin from harmful UV rays. SPF protects the skin from reddening and surface burns and reduces the chances of ageing, wrinkles, and cancer.
Sunscreen SPF are divided into three categories - 15 (mild), 15-30 (moderate), and 30+ (high protection). For example, if a normal skin turns red within a minute’s exposure to the sun, apply SPF 15 sunscreen longer. Whereas, if it takes 10 minutes for the skin to get burnt, consider applying SPF 30 sunscreen.