Most people confuse the primary colors of light with the primary colors of paints. These two concepts are very different.

There are three colors of light that can be mixed to make all other colors that we can see. These colors are red, blue, and green. This is why red, blue, and green are known as the three primary colors of light. Television sets and projection units use this concept to make all the colors you see. A projection television is a perfect example. There are three lights on a projection television set one red, one blue, and one green. They each project a picture on the screen and these three seperate pictures mix to create the overall picture you see.

This method of creating a final color is done by adding different colors of light together. (hence the title of this web page - color by addition)

As shown by the example, the three primary colors mix to make the three secondary colors in these ways when mixed in equal amounts.
Blue + Red = Magenta
Blue + Green = Cyan
Green + Red = Yellow

All primary colors added together make white light. You can see this in action in the picture to the left when all three spotlights occupy the same space.