Melanin is a pigment that is responsible for the colour of the skin, hair, and eyes in humans and other animals. It is produced by cells called melanocytes, which are primarily found in the skin but also in other tissues, such as the eyes and inner ear. The amount and type of melanin present in an individual's skin, hair, and eyes determine their overall pigmentation. Melanin serves to protect the skin as it absorbs harmful UV rays, reducing oxidative stress and consequently the damage to the cells.

The production and distribution of melanin are influenced by genetic factors, exposure to ultraviolet (UV) radiation from the sun (sun spots), hormonal changes, post-inflammatory responses to acne or skin trauma, and the natural ageing process. Hyperpigmentation refers to excessive melanin production, caused by overactivity of melanocytes, and can manifest as dark spots, melasma, freckles, or uneven skin tone within the epidermis.

Green light has been found to stimulate cell turnover and promote the formation of new blood vessels within the epidermis of the skin. Its also been shown to improve the appearance of hyperpigmentation, by breaking down and reducing the production of melanin.