What is SPF? SPF stands for sun protection factor. This rating is used in sunscreens to block UVB rays. UVB radiations, which are the main cause of sun-related damage. SPF 30 blocks 96.7 percent of UVB rays, while SPF 50 blocks 98.6 percent. Let's discuss SPF in more detail. Here https://www.topscosmetics.uk/product-category/skincare/moisturisers/spf-moisturisers/