What characteristic is common to all types of haircolor?

The characteristic common to all types of haircolor is that they are designed to alter the natural hair color. This fundamental purpose is what distinguishes hair color products from other hair treatments; their primary function is to change the existing pigment in the hair.

Regardless of whether a specific product is a permanent, semi-permanent, or temporary color, all serve the primary goal of modifying the natural color of the hair, allowing for creativity and personalization in hair styling. By doing so, they enable individuals to achieve their desired look and express their identity through hair color.

Options that suggest all haircolors can lighten hair, penetrate the hair shaft, or be used on any hair type do not accurately reflect the nature of all haircolor products. For instance, not all color products are capable of lightening hair—some may only deposit color. Additionally, while many products penetrate the hair shaft to varying degrees, not all formulations accomplish this in the same manner. Finally, hair color products may be formulated with specific hair types in mind, leading to limitations in their application, making these options less universally applicable compared to the goal of altering natural hair color.