Moles are caused when pigment-producing melanocyte cells grow in groups instead of spreading throughout the skin. They can develop anywhere on the body and are typically brown but may also be black, pink, red, blue or tan.

Moles can darken or lighten in color — and even fade — over time. They're round and oval and primarily develop during childhood and adolescence.

Factors such as age, hormonal changes, genetics and sun exposure are causes for moles to develop. Most moles are common and harmless, but there is a risk of developing melanoma, so it's important to monitor any changes in their appearance.