When your skin is exposed to the sun for long periods of time, it damages healthy cells. Without sun protection, this damage can build up. In time, you see signs of sun damage like freckles, age spots, and wrinkles. Some people develop precancerous skin growths, skin cancer, or both. Every time you go outdoors without sun protection or use a tanning bed, ultraviolet (UV) light damages your skin. With time, this damage builds up and you see changes to your skin, which can make you look years older than you naturally would.
These changes include:
Blotchy or ruddy complexion
Cited from the Mayo Clinic & the American Academy of Dermatology