The following chapter introduces the readers to the complexity of colour perception, emphasizing that colour is not an intrinsic property of objects, but a perceptual quality derived from the interaction between light and HVS, the human visual system. It analyses how light, interacting with material surfaces, influences perception through reflection, transmission, and diffusion. The chapter describes the trichromatic theory, which explains that three types of retinal cones (sensitive to short, medium, and long wavelengths) allow the perception of a wide range of colours. Phenomena like metamerism, where different colours appear similar under specific lighting, are also considered, as well as review Hering's opponent-process theory. Finally, the authors discuss the role of chromatic induction where adjacent colours influence the perception of a given colour, demonstrating how colour perception is a dynamic and contextual process.