If you look on a basic color wheel you will see that he is separated on 12 parts (colors): primary, secondary and tertiary colors and their variations in brightness.

Primary Colors

With Red on top circle of color consists of three primary colors: Red, Yellow and Blue.

Those three colors close triangle in a circle of colors.

Secondary Colors

Three secondary colors are: Orange, Purple and Green.

They became by mixing primary colors and in a circle of color they are between them closing another triangle.

Tertiary Colors

Tertiary colors who are result of mixing primary and secondary colors are: Red orange, Yellow orange, Yellow green, Blue green, Blue purple and Red purple.

Complementary Colors

If you look the circle of color, the color that is diagonally opposite of one color is compliment of that color.

Complementary couples are: Red-Green, Blue-Orange, and Yellow-Purple.

Complementary colors conflict each other because none contains no small part of the other-so when they are together in one place both strongly emphasizes.