Heading for the beach? Always use a sunscreen that protects your skin against UVA and UVB rays. The ingredients in sunscreen absorb ultraviolet radiation by forming a barrier on the skin’s surface. Energy from sunlight is converted to heat, and is dissipated harmlessly.
Sunscreens work best if they're used properly: shake the bottle before using it; rub it in well to ensure even coverage; when applying to your face, rub into hands, then apply to the face; wait ten minutes before having a swim, or it’ll just wash off; and reapply after swimming, drying off with a towel, or sweating.