The durability of wood is ranked by the Janka hardness rating, which measures the pounds of force per square inch needed to embed a steel ball in the surface. The higher the number, the harder the wood and the more resistant it is to dents and scratches. To put the figures in perspective, consider this: A 125-pound woman in high heels exerts 2,000 pounds of force per square inch on a wood floor. Keep in mind that the noticeable grain of certain woods will hide wear and tear better than others. That said, you can always enforce a no-shoes policy in your home if you fall for the look of one of the softer species.