Do you have freckles? If you don’t, chances are you probably know someone who does. But what are they exactly?

Freckles appear on the skin as small tan or light brown spots. While they usually appear on the face, they can also be found on any skin exposed to the sun, such as the neck and shoulders.

Freckles are natural and not harmful. Even though some people with freckles don’t like them and want to get rid of them, they’re certainly not a sign of any health problems.

Freckles are just skin cells that contain a pigment (color) called “melanin.” Melanin is a chemical made by skin cells called “melanocytes.” Melanin helps to protect the skin from the sun’s harmful ultraviolet rays by reflecting or absorbing them.

Freckles are triggered by exposure to sunlight. The sun’s ultraviolet radiation causes melanocytes to make more melanin, which can cause freckles to appear or become darker.

While anyone can have freckles, they are genetic. So if your parents have freckles, there’s a good chance you will, too. People with fair complexions (skin and eyes that are light in color) tend to have more freckles than people with darker complexions.

The melanin in your skin is what makes you look tan. The more melanin you have in your skin, the easier it is to get a tan.

People with fair complexions have less melanin in their skin to start with. When sunlight causes their melanocytes to make more melanin, they often develop freckles instead of getting an even suntan like people with darker complexions.

Some people have freckles that fade away in the winter and return every summer. Other people have freckles year-round. Freckles often tend to fade when people get older.