Carotenoids have traditionally been subscribed to their role as accessory pigments in photosynthesis. However, the large and growing body of literature investigated on the field have revealed that carotenoids fulfil a plethora of essential roles in plants but also in animals and in humans. Recent studies emphasizing the functional role of molecules derived from carotenoids oxidation as β-cyclocitral or dihydroactinidiolide led to a renewed interest, opening a new era for the carotenoids research. This review brings together the knowledge obtained so far regarding diversity and functions of carotenoids, highlighting carotenoids versatility and the remarkable parallel roles of carotenoids in both plants and in animals. Evolutionary aspects and the responses of carotenoids to biotic and abiotic stresses are discussed. Furthermore, we outline the way in which one can understand the environmental regulation to enhance carotenoid content in food. In addition, an up-to-date overview of carotenoids as elements of information storage system for the responses to environmental signals is provided together with suggestions for future directions of research.