What does "hair density" refer to?

Hair density specifically refers to the number of hairs per square inch on the scalp. This measurement provides insight into how full or sparse someone's hair may appear. People with high hair density have a larger number of hair follicles in a given area, resulting in a thicker, fuller look. In contrast, those with low hair density will have fewer hair follicles within the same area, which can result in a more thinning appearance. Understanding hair density is crucial for hairdressers and cosmetologists when designing hairstyles or selecting hair products, as it impacts the overall styling and aesthetic of an individual's hair.

The other choices pertain to different aspects of hair but do not define hair density. The thickness of individual hair strands relates to hair texture, while hair length measures how long the hair is from the root to the tip. The overall weight of the hair is not a standard measure used in hair analysis, as it does not directly correlate to how many hair strands are present in a given area.