Hair density is the amount of hair strands on the head. Generally, it is measured by counting the number of hair strands found in one square inch (or 6.5 square centimeters) of scalp. When a stylist tells you that you have thick hair, it is high density he/she is describing.
The main consideration of hair density is in styling. Thick hair is well suited to layered styles, while thin hair is often better suited to more blunt styles. People with thin hair often prefer styles with added curl to give an illusion of more hair.
While there is not a true ethnic or racial determiner of hair density, it has been found that blondes tend to have the greatest hair density, while redheads have the lowest.
Hair texture Hair elasticity
Hair porosity Hair wave pattern