Freckles (ephilides) are small flat brown marks usually seen on the face and other sun-exposed areas of people with fair skin.
The brown color is due to a collection of dark pigment in the skin called "melanin". This melanin is created by specialized skin cells called melanocytes. When exposed to the sun, these melanocytes produce more melanin which explains why freckles tend to become more apparent during the summer, and fade in the winter.
Freckles tend to become less apparent with age.
Consistent use of sunscreen and sun avoidance measures can help prevent the growth of new freckles and the darkening of existing freckles.