Opsins are light-sensitive proteins found in the photoreceptor cells of the eyes. They play a crucial role in vision by absorbing light and initiating the process of converting light signals into electrical signals that the brain can interpret. Different types of opsins are sensitive to various wavelengths of light, allowing organisms to perceive a range of colors. In addition to their role in vision, opsins are also involved in other biological processes, such as circadian rhythms and non-visual light responses. They are found in many organisms, including humans, animals, and some microorganisms, highlighting their importance in both vision and broader biological functions.