Skin damage from sunlight

What happens in the skin when exposed to ultraviolet rays?
UV rays can penetrate the skin and are absorbed (swallowed). UVB is about 90 percent already in the stratum corneum, while UVA also penetrates deeper layers of skin.
The skin browning is the main bodies own defense mechanism against the harmful effects of UV rays. It is an increased pigmentation of the skin due to storage of melanin pigment (the body's own skin pigment) into the upper layers of skin.