What is the primary purpose of using a developer in hair coloring?

The primary purpose of using a developer in hair coloring is to lighten hair. When mixed with hair color or bleach, the developer activates the color or lightening agent, allowing it to penetrate the hair cuticle and alter the natural pigments. Developers contain hydrogen peroxide, which plays a crucial role in oxidation, both lightening the natural melanin in the hair and allowing the new color to bond properly with the hair. This chemical process is essential for achieving the desired shade and ensuring long-lasting results in the hair coloring process.