A color wheel is also sometimes called a color circle. The colors are organized around the circle in a way to show the relationship between them. Primary colors include blue, yellow and red. Secondary colors are green, orange and violet. There are also colors referred to as tertiary colors and this includes red--orange, red--violet, yellow--orange, yellow--green, blue--violet and blue--green.
The three primary colors are situated on the color wheel equally spaced out from one another. In between these primary colors on the color wheel are the colors that can be made by combining those two primary colors. For example, the primary color yellow is usually situated near the top of the color wheel. Between yellow and the next primary color, red, there will be the colors that would be found when yellow and red are combine. This would include orange-yellow, orange, orange-red.
The color wheel not only shows the relationship between all of the colors but can also be used to choose colors for art or design based on how the colors complement each other on the color wheel.