Which type of haircut utilizes a traveling guide for length modifications?

The layered haircut utilizes a traveling guide for length modifications, which is essential for achieving the desired texture and movement within the hair. In layered haircuts, the stylist lifts sections of hair and cuts them while using a traveling guide, meaning they refer back to previously cut sections as they progress. This approach is crucial because it allows for a consistent length in layers while providing the fluidity and dimension characteristic of this style.

In contrast, a blunt haircut has a straight and even line with no layers, so there is no need for a traveling guide. A graduated haircut, while it does involve angle and length modification, often follows a more structured approach rather than relying on a traveling guide throughout the process. Thus, layered haircuts are particularly defined by their use of a traveling guide, making it the correct answer in this context.