Solar lentigines, commonly known as age spots or liver spots, are flat, brown, or black spots that appear on the skin due to prolonged exposure to sunlight. They are most often found on areas that receive the most sun, such as the face, hands, and arms. These spots are usually harmless and do not require treatment. The development of solar lentigines is a result of increased melanin production in the skin, which is the pigment responsible for skin color. While they are more common in older adults, younger individuals can also develop them, especially if they have significant sun exposure.