The easiest method is to use felt pads or furniture glides under the legs. These small stick-on pads are cheap, easy to apply and make a big difference, especially on wood, laminate and vinyl floors. They spread the weight a little and prevent sharp edges from digging in or scratching when furniture moves.
Before sticking pads, clean the bottom of each leg so dust doesn’t reduce the glue’s grip. Check them every few months; pads can wear down or fall off, especially on chairs that move a lot.
For very heavy items like pianos or large cabinets, you can use wider protective cups or rubber pads designed for that job. In areas prone to sliding, like under sofas on smooth floors, combining pads with a rug can help.
Protecting floors from the start is much cheaper than refinishing or replacing them later because of deep dents and scratches. It’s a small step most people only appreciate after they’ve seen the damage.