The Janka Hardness Rating of wood is a relative measurement of its resistance to impact and wear. Therefore, the rating gives prospective buyers a numerical representation of the wood's durability. This is important for matching flooring material to its intended usage. Higher levels of foot traffic would require a more durable species and thus one with a higher Janka rating.
While Janka values give a general sense of hardness, many other factors also contribute to a wood floor's durability, including the type of cut (i.e. plainsawn, quartersawn), denseness of cell structure and finish used.