We perceive colors with specially adapted photoreceptor cells in our retinas called cones. There are three types of cone cells (from which the name for our ability to see color – trichromatic vision –is derived), and each is tuned to detect light in a specific range of wavelengths: long, with sensitivity peaking at red light; medium, tuned to green light; and short, which respond best to blue light. The one million (yes, million!) colors we are capable of seeing each correspond to different combinations of cone activation in response to light. Often, men (and, occasionally, women) who are colorblind have a genetic abnormality that results in the lack of one of the three types of cones. With only two cones, the full range of light wavelengths are not detected, and fewer combinations of activation lead to fewer perceived colors.