Individuals are urged to guard against sunburns and skin cancer by applying a sunscreen. But what does SPF and the various numbers associated with it mean? SPF refers to sun protection factor. The SPF rating, according to Verywell Health, refers to how long a person can stay in the sun without getting burned while wearing the sunscreen compared to how long he or she could stay in the sun before burning without wearing sunscreen. For example, if you normally burn after 10 minutes in the sun and you apply an SPF 15 product, it will take 15 times longer to burn in the sun, or 150 minutes (2.5 hours). Wearing a higher SPF product doesn't protect you better, it does protect you for longer durations. Therefore, you could conceivably wear an SPF 5 and with frequent reapplication, get the same level of protection as wearing SPF 45. Higher number SPF products may be preferable since people can easily get distracted or forget to apply sunscreen regularly while outdoors. But experts recommend reapplication of sunscreen every two hours, regardless of the SPF number on your sunscreen bottle