Solid Hardwood

These floors will be one solid piece of hardwood. They can be refinished many times and will probably be there as long as the house is standing.
Some solid hardwood floors can be nailed or stapled. Be sure to follow the manufacturer's recommendations
Be careful with wide plank solid floors. In the winter you may see gaps; in the summer you may see buckling. This is normal with solid floors and is not a defect. If that might bother you, take a look at Engineered Wood. These floors will be more stable.