Which tool is essential for making precise parts in hair?

The essential tool for making precise parts in hair is the comb. A comb allows for accurate sectioning and parting, which is crucial for achieving clean lines and well-defined styles during a haircut. It provides the necessary control to lift and separate the hair in specific areas, ensuring that the stylist can create uniform sections and maintain precision throughout the cutting process.

While other tools like shears and razors are vital for cutting and texturizing hair, they do not serve the primary function of parting hair. The comb is specifically designed for manipulating and organizing hair for various styling techniques, making it the most critical tool for the task of parting hair accurately.