Which type of lines is typically used to create a one-length haircut?

In haircutting, the use of horizontal lines is essential for achieving a one-length haircut. This technique involves cutting the hair straight across, which creates a uniform length throughout the hair strand. The horizontal line allows the barber to maintain an even weight and structure, ensuring that the hair lies flat without layers.

This method is effective for creating styles that have a blunt finish, often seen in classic cuts, and provides a strong, solid foundation to the haircut. By using horizontal lines, the barber can easily gauge the length across the head and ensure that all sections of hair are cut to the same length, resulting in a balanced and symmetrical look.