The three primary colors are red, blue and yellow. These colors cannot be made by any combination of other colors. The mixture of these colors together makes secondary colors and all other colors out there. Look here for more information: http://en.wikipedia.org/wiki/Primary_color
The three primary colors are: red, blue and yellow. All other colors (called secondary colors) are made by mixing two or more of these colors. Also, black and white are mixed with primary colors or secondary colors to make different hues of colors.