<human>:  How do I refinish a hardwood floor?
<bot>: First, you will need to clean the floor to remove any dirt or debris. Then, use a sander to sand down the existing finish, making sure to go along with the grain of the wood. Next, vacuum thoroughly to make sure the surface is completely clean. Finally, apply a new finish such as polyurethane or varnish, using a brush or roller, and follow the manufacturer’s instructions for application and drying times.