The roles of carotenoids and lutein in photosynthesis are to absorb and transfer light energy and to protect chlorophyll. Carotenoids and lutein (collectively known as carotenoids) can transfer the absorbed light energy to the special state of chlorophyll A for its conversion of light energy, and therefore with lutein and other known as "antenna pigments". In addition, carotenoids have the function of protecting chlorophyll.

Carotenoids are commonly found in the yellow, orange-red, or red pigments of animals, higher plants, fungi, and algae. Carotenoids are the main source of vitamin A in the body, and also have antioxidant, immunomodulatory, anti-cancer, and anti-aging effects.

Expanded:

Discoverers of new carotenoids generally choose names that reflect their source or properties, such as maximum wavelength of absorption, when naming new carotenoids. Thus, pigments from carrots are called carotenoids, those from violets are called "purple xanthophylls," and the major pigment from seaweeds is called lignocellulose.

These names can be referred to as the customary nomenclature for carotenoids. Historically, because there was often a delay of many years between the first isolation of a carotenoid and the determination of its structure, there was little choice but to use its customary name.

Even after the structure is known, many researchers are reluctant to abandon the use of the customary names, mainly because they are familiar, short, and easy to use on a daily basis.