Which tool is primarily used for creating straight lines in haircutting?

In haircutting, shears are specifically designed to create straight lines and precise cuts. They feature sharp blades that enable the stylist to make clean cuts through the hair, allowing for the desired length and shape to be achieved with accuracy. The use of shears is fundamental in cutting straight lines, as they provide control over the tension and angle at which the hair is cut, ensuring that each section of hair is uniform.

Other tools may serve different purposes in the hairstyling process. For example, a razor is typically used for texturizing and creating softer, more blended lines, while texturizing shears are specifically designed to thin out hair and add texture rather than create straight lines. A comb is essential for sectioning and managing hair during the cutting process but does not perform any cutting itself. Thus, shears are the most suitable tool for achieving the precision required when creating straight lines in haircutting.