In hair coloring, what does the term "developer" refer to?

In hair coloring, the term "developer" specifically refers to a solution that activates the color. This is a crucial component in the hair coloring process, as it contains hydrogen peroxide, which helps open the hair cuticle and allows the color to penetrate the hair shaft. The developer plays a vital role in the chemical reaction that leads to the desired shade, determining the lift or deposit of color in the hair.

Using a developer is essential for various hair color applications, whether it's to lighten natural hair color or to deposit vibrant shades. It is available in different volumes, which indicate the level of strength and the degree of lift it can provide. A higher volume developer is typically used for lifting natural color, while a lower volume may be used for deposit-only color treatments.

The other options relate to products in hair care but do not directly describe the function of a developer in hair coloring. Nourishing the scalp, conditioning colored hair, or toning treatments serve different purposes in the overall hair care and coloring spectrum, but they do not activate or facilitate the color application in the same way that a developer does.