What are the three primary categories of hair?

The three primary categories of hair type are straight, wavy, and curly. This classification is based on the natural shape of the hair strands which is determined by the follicle's shape and the angle at which it grows out of the scalp.

Straight hair has a smooth texture and lies flat against the scalp, which is typically associated with round follicles. Wavy hair forms a gentle curve or wave pattern, stemming from an oval-shaped follicle. Curly hair displays a more pronounced spiral or zigzag pattern, resulting from a significantly oval or even asymmetrical follicle shape.

Understanding these three categories helps in selecting appropriate hair care products and techniques, as each hair type has unique needs regarding moisture, styling, and maintenance. This classification does not focus on other characteristics like the hair's porosity or texture, but rather on its overall shape and pattern, making it fundamental in hair care and styling education.