My favorite color is yellow. It's flashy, turns heads, and in a way I find it soothing. Do you like yellow things?
Yellow is between two primary colors on the spectrum.  They also have really expensive yellow light lasers.
You can get lasers made with yellow light? That's awesome! Why would you want yellow laser light though?
Yellow
Yellow is the color between orange and green on the spectrum of visible light. It is evoked by light with a dominant wavelength of roughly 570590 nm. It is a primary color in subtractive color systems, used in painting or color printing. In the RGB color model, used to create colors on television and computer screens, yellow is a secondary color made by combining red and green at equal intensity. Carotenoids give the characteristic yellow color to autumn leaves, corn, canaries, daffodils, and lemons, as well
skin — a foundation that appears very yellow in the bottle may apply much less yellow, or not appear yellow at all. Trying the color on in stores like Ulta or Sephora is usually the best way to find an accurate match.
Modern formulations Color Shade Range.
Another issue that can arise when searching for your foundation shade is there not being a shade for you. This may be because you cannot tell the undertone of your skin, but it can also be from the selected foundation not being made light or dark