Not every type of skin reacts in the same way when exposed to the sun. Dermatologists therefore make a distinction between six skin types with different intrinsic protection times. Skin type 5 and 6 normally do not get sunburnt and are thus not mentioned here.
The table below gives an overview on the four skin tpyes at risk. It indicates their intrinsic protection time and the possible extension of the same by wearing a textile with a UPF of 20: