If your hair is anything like mine, then you know that you could literally pour a cup of water or your hair and see less than a tablespoon come out. Why is that? Even if my hair is well moisturized, I can still add an entire cup of water.
Well its called hair porosity. Hair Porosity is how well water moves through your hair, or how well your hair holds water. Porosity comes from the Greek word poro which literally means passage.
This is one of those subcategories beyond learning your hair type. You and another individual may have identical curls, but since your porosity is lower or higher, you may require more product for certain styles.