The primary colors are red, blue, and yellow. These colors are fundamental because they cannot be created by mixing other colors together. Instead, they serve as the building blocks for creating a wide range of other colors through mixing. For example, combining red and blue results in purple, red and yellow create orange, while blue and yellow yield green. The concept of primary colors is essential in art, design, and color theory, allowing artists and designers to mix and create a diverse palette of colors to work with in their projects.