Primary colors

These are red, blue and yellow. In theory, you can make any color from these three primaries (except white, which is really an absence of color). In practice, it depends on what red, blue or yellow you start with, but we are not mixing paints here, so just remember that the primary colors are red, blue and yellow. You'll learn why in the next step.

The secondary colors are the colors you get from mixing equal amounts of any two primaries. (If the primaries are pure, mixing all three will give you black.)

The secondaries are purple, orange and green.

Now why do you care?

Well, primaries and secondaries together give us complementary colors. The complement of the color is the color directly across from it on the color wheel, or if starting with a primary, the color made from mixing the other two primaries. So essentially a color and its complement contain all of the primaries between them.

Red's compliment is green (Merry Christmas!). Yellow's complement is purple. Blue's complement is orange.
This is as much contrast as you can get between colors of the same value (brightness or darkness). So if you want to make a bold statement, the primaries are a treat.