Vellus hairs are usually characterized by what feature compared to terminal hairs?

Vellus hairs are typically defined by their smaller diameter compared to terminal hairs. This characteristic is crucial in distinguishing the two types of hair. Vellus hairs are fine, soft, and usually sparse, and they cover much of the body's surface, providing warmth and some level of protection. In contrast, terminal hairs are thicker, coarser, and often darker, typically found in areas such as the scalp, beard, and armpits. The difference in diameter is significant because it affects the hair's texture and appearance, contributing to the overall aesthetic and function of hair in different body regions.