What characteristic of hair does "texture" refer to?

Texture refers specifically to the thickness or diameter of the individual strands of hair. It encompasses how fine, medium, or coarse the hair is, which affects various aspects, including styling, manageability, and the overall appearance of the hair. Understanding hair texture is crucial for selecting appropriate products and techniques that will work best for an individual's hair type.

In the context of the other options, while color, length, and the way hair feels at touch are all important characteristics in hair care and style selection, they do not define texture. Color pertains to the hue of the hair, length indicates how long the hair is, and the way hair feels could relate to its softness or roughness but does not capture the specific quality of texture that is concerned with the diameter of the individual strands.