M-cones, or medium-wavelength cones, are one of the three types of photoreceptor cells in the human retina. They are primarily responsible for detecting green light and play a crucial role in color vision. M-cones work alongside S-cones, which detect blue light, and L-cones, which detect red light, to help the brain perceive a full spectrum of colors. These cones contain photopigments that are sensitive to wavelengths around 530 nanometers. When light hits the M-cones, it triggers a chemical reaction that sends signals to the brain, allowing us to interpret colors. The proper functioning of M-cones is essential for tasks like distinguishing between different shades of green and other colors.