Wood floors can add value to your home. They continue to grow in popularity, but as they do, so too do does the list of options available to you. As with anything, it's important to do your homework. Here is a very brief outline of the basic types available. From here, there are still things to think about: colour, board size, actual type of wood, etc. As with anything, your best bet to consult a professional.
Unfinished. This type requires you or your installer to sand and apply a finish. If you want a specific colour or style, or you're trying to match existing flooring, this might be the best option for you.
Factory finished. As the name suggests, this is flooring that has its finish applied in the factory. Although it is more expensive, factory finished flooring can be installed faster and can be walked upon immediately.
Solid. This is flooring that is made from a solid piece of wood, top to bottom. The advantage is that it can be sanded and refinished many times over the years, or even decades.
Engineered. This is flooring that is made of thin layers of wood pressed together. It can be engineered to be very durable and expand and contract less than solid flooring.
The type you choose depends on your needs. Talk to your dealer or contractor about your specific application.