Moles, also known as nevi, are a common type of skin growth. They are small in size, have dark brown spots, and are usually caused by clusters of pigment-forming cells. Most adults will have 10-40 moles grow on their bodies. It can be darkened due to sun exposure or pregnancy. Moles can appear anywhere on your skin, but it is harmless. However, it is important to exclude skin cancers prior to mole removal treatment.