Freckles are small, flat, and circular spots that are usually tan or light brown in color. They are commonly found on the face, arms, and upper body, and are more prominent in people with fair skin. Freckles are caused by an increase in melanin production in the skin, which is the pigment responsible for skin color. The development of freckles is largely determined by genetics, although sun exposure can also play a role. People with a genetic predisposition to freckles have more active melanocytes, which are the cells that produce melanin. When the skin is exposed to sunlight, these cells produce more melanin in an effort to protect the skin from UV radiation. Freckles are more common in people with fair skin, as they have less melanin in their skin to begin with, and are more susceptible to the damaging effects of UV radiation. They may also become more prominent during the summer months or after spending time in the sun. While freckles are generally harmless, it's important to protect the skin from sun damage by wearing sunscreen, protective clothing, and avoiding prolonged sun exposure. People with a large number of freckles, or those with freckles that are changing in appearance.