Freckles are small brown spots on your skin, often in areas that get sun exposure. In most cases, freckles are harmless. They form as a result of overproduction of melanin, which is responsible for skin and hair color (pigmentation). Overall, freckles come from ultraviolet (UV) radiation stimulation.

There are two categories of freckles: ephelides and solar lentigines. Ephelides are the common type most people think of as freckles. Solar lentigines are dark patches of skin that develop during adulthood. This includes freckles, aging spots, and sunspots. The two types of freckles can look similar but differ in other ways such as their development.