Which color is typically not included in the definition of primary colors?

In color theory, primary colors are defined as the foundational colors that can be combined to create a broad spectrum of other colors. These primary colors vary depending on the color model being used. In the traditional subtractive color model, which is often used in art and design, the primary colors are red, yellow, and blue. Green is not a primary color in this model; instead, it is a secondary color that can be made by mixing blue and yellow.

This is why the color green does not belong in the group considered as primary colors. By understanding the definitions and relationships between colors within the context of color theory, one can appreciate why green is categorized differently than red, yellow, and blue.