Red, yellow and blue are traditional primary colors.
Secondary colors are combinations of two primary colors. Yellow and blue combine to make green, red and blue combine to make purple, and yellow and red combine to make orange. Green, purple and orange are secondary colors.
Tertiary colors are combinations of three colors created from one secondary and one primary color. Yellow-green, blue-green, blue-purple, red-purple, orange-red and yellow-orange are tertiary colors.
Art teachers arrange colors in a wheel shape to demonstrate basic color theory. Colors opposite from each other on the wheel are complementary: when used together they create a sense of excitement or disharmony. Colors neighboring each other on the wheel are analogous, when used together they create a sense of harmony.
Artists create subtractive colors by mixing pigment. Subtractive color is the basis for both secondary and tertiary colors, but artists use color mixing to explore a much wider variety of colors. Mixing pigment creates colors such as magenta, cyan and teal.
These colors are on the "louder" side of the spectrum. Shades of yellows, oranges and reds are warm colors.
These colors are "quieter" to the eye. Greens, blues and purples are cool colors.
There are many ways to arrange colors besides complementary, analogous, warm and cool color schemes. Achromatic schemes use white, black, and shades of gray. Monochromatic schemes use light and dark shades of the same color.