By now, I hope you all know the SPF stands for sun protection factor. A few sunscreen labels also list a "PA" ranking, like this Shiseido sunscreen pictured. PA ranking refers to the amount of protection the sunscreen offers from the UVA rays, since SPF just ranks protection from UVB rays. PA rankings are listed as PA+, PA++ or PA+++ with the more plus symbols the more protection from UVA Read more