Wood floors have their own charm, warmth and character. At times they can appear to be very durable, then one day scratches are noticed and no one seems to know why.
Minimizing potential damage from furniture is easy and straight forward. The bottom of chairs, tables, wood items should have glides, preferably hard plastic. They have a single nail shank embedded into the plastic and are easy to install. Every once in a while turn a chair upside down and check the glide to see if it is getting worn. If so, replace it.
Chrome glides were the standard prior to the development of plastic. They too will help protect a wood surface from scratches. However when they wear down, or become rusty, the three pronged kind can be harder to replace.