Carotenoids, a type of pigment, are used in photosynthesis to absorb sunlight for plants to convert into energy. Pigments are substances that absorb light in a specific spectrum. Carotenoids typically absorb light in the violet to green light spectrum, which is from about 400 to 550 nanometers.
In addition to carotenoids, plants often also have other types of pigments, such as chlorophylls and phycobilins. While carotenoids typically appear to be orange, red or yellow, chlorophylls are mostly green and phycobilins are a hue of red. Each type of pigment absorbs a different part of the light spectrum. Together, they are able to absorb enough light so that the plant can sustain itself through photosynthesis.