This is the color wheel in its full glory.To understand it a little bit better, we can break it down by color.

  

Three Primary Colors - Red, Blue and Yellow.   All colours come from some combination of two or more of these colors. 

Three Secondary Colors - Orange, Green, and Violet.  These colors are made by two primary colors mixed together. yellow + red = orange; yellow + blue = green; red + blue = violet

These color combinations are called intermediate colours.  Intermediate colors lie between the primary and secondary colors on the color wheel. Intermediate colors are made by mixing together one primary and one secondary color.

The combination of primary, secondary and intermediate colors creates the color wheel.