Real wood will expand and contract with change in humidity, leaving small cracks in between the boards. This affect can be minimized with the use of humidity control in the home. 

To protect floors from dirt or water, place rugs at entry points to help trap grit and absorb moisture that may damage the finish. However, note that rugs with rubber bottoms or non-skid pads may leave an imprint on the floor. Natural fiber rugs are a safer choice. 

Regularly sweep or vacuum the floor with a soft brush to prevent abrasive dirt and dust from accumulating and scratching the finish. Vacuuming should only be done with machines that have a hard surface setting to prevent damage from the rollers. 

Don't Damp Mop: Use only the cleaning products designed specifically for hardwood floors.

Never use wax, oil-based detergent or any other household cleaners on the floors. These may dull or damage the finish, leaving a greasy film and making the floor slippery and more difficult to clean.  Do not use spray polishes or other cleaners that are designed for other types of wood furnishings.

Wipe Spills Immediately. Be especially attentive sink, dishwasher, stove tops and dining rooms, which are more prone to harmful spills.

Add felt pads to all furniture and chair legs to prevent damage to the floor. Replace the felt pads when dirty or worn. For extremely heavy objects, use wide, non-staining rubber cups.

Damaged or worn high heel shoes may expose a metal tip which is certain to damage the surface finish. Keep high heel shoes in good condition. 

Pet's nails can scratch and mar wood floors. Keep dog and cat nails properly trimmed to protect your floor.

Protect your floor against direct sunlight or any intense source of artificial lighting. Over time, intense natural and artificial light will discolor hardwood floors.