L-cones, or long-wavelength cones, are a type of photoreceptor cell found in the retina of the eye. They are sensitive to light in the red part of the spectrum, allowing humans to perceive colors like red and orange. L-cones work alongside other types of cones, specifically M-cones and S-cones, to enable color vision. These cells play a crucial role in the trichromatic theory of color vision, which explains how the combination of signals from the three types of cones results in the perception of a wide range of colors. L-cones are essential for distinguishing colors in various lighting conditions.