Carotenoids are a class of pigments found in plants, algae, and some bacteria, responsible for the bright red, orange, and yellow colors in many fruits and vegetables. They play a crucial role in photosynthesis and protect plants from oxidative damage. Carotenoids also have health benefits for humans, as they are antioxidants and can be converted into vitamin A in the body. Common carotenoids include beta-carotene, lutein, and zeaxanthin.