Color Vision

Color vision is pretty complicated. If you're not color-deficient or color-blind then it's hard to understand what color-blind people see. There are four kinds of color vision:

Trichromat
Regular vision is Trichromatic - it uses all three colour pigments (red/green/blue).

Anomalous Trichromat
People with Anomalous Trichromatic vision use all three color receptors but reception of one pigment is misaligned.
Protanomaly: reduced red sensitivity.
Deuteranomaly: reduced green sensitivity.
Tritanomaly: reduced blue sensitivity.

Dichromat
People with Dichromatic vision use only 2 of the 3 visual pigments - red, green or blue is missing.
Protanopia: unable to receive red.
Deuteranopia: unable to receive green.
Tritanopia: unable to receive blue.

Monochromat (Achromatopsia)
People with Monochromatic vision can only see one color, so their vision contains no 'color'.
Typical Monochromatic: unable to combine colors. Fully grayscale. Also known as Rod Monochromat.
Atypical Monochromatic: very low color recognition. Also known as Cone Monochromat.

Note: You might also like to do a bit of research into tetrachromats, who have four color pigments instead of the usual three!