Broad-spectrum UV protection means that the product protects against both UVA and UVB rays.
SPF is the same as sun factor, and indicates protection against UVB rays.
SPF is a measure of how long the skin can be exposed to UV rays without turning red, compared to if you were not wearing sunscreen.
SPF is a mathematical formula that is not linear. The number in SPF shows the strength of the sun protective effect. Slightly simplified, you can say that SPF15 protects approx. 93% of UVB rays, SPF30 protects approx. against 97% of UVB rays, while SPF50 protects approx. against 98% of UVB rays. High sun factor means that a product has either SPF30 or SPF50. The Swedish Cancer Society always recommends using factor 30 or higher.
The sun protective effect decreases over time. You must repeat the application approx. 2 every hour if you stay in the sun. Remember that you must use enough product to achieve the protection indicated on the product. For the face and neck, it is recommended to use cream corresponding to the length of 2 fingers.