Fun Fact of the Day: Our retinas contain two types of light sensitive cells, rods and cones. The rods are used to detect light intensity and brightness while the cones are responsible for color vision. We have three types of cones capable of recognizing red, green and blue. These are the primary colors, and combining any two will give us the secondary colors of green, cyan and magenta. All these hues in different combinations and intensities give us the many colors that we know and see every day.