Solar lentigo, commonly known as age spots or liver spots, are flat, brown, or black patches that appear on the skin due to prolonged exposure to sunlight. They are most often found on areas frequently exposed to the sun, such as the face, hands, and arms. These spots are a result of an increase in melanin, the pigment responsible for skin color. While solar lentigines are generally harmless and do not require treatment, they can be a sign of sun damage. It's important to protect the skin from further sun exposure to prevent new spots from forming.