What type of color service lightens the hair?

The type of color service that specifically focuses on lightening the hair is bleaching. Bleaching works by removing the natural pigments in the hair, resulting in a lighter shade. This chemical process involves the use of strong oxidizing agents, typically hydrogen peroxide, which breaks down the melanin in the hair strands, effectively lightening them.

While highlights and permanent hair color may also create lighter effects, they do not solely focus on the lightening process in the same way that bleaching does. Highlights are a technique used to add lighter strands to the hair, while permanent hair color can lighten hair but is more commonly used to change the overall tone or add color. Semipermanent color usually does not lighten the hair as it is designed to add color without the strong chemical actions involved in bleaching. Therefore, the most accurate answer to the question is bleaching, as it is the process specifically aimed at lightening the hair.