Wood flooring comes in three different formats - Solid, Engineered and Floating. What is the difference?

National Wood Flooring Association

,
woodfloors.org/consumer/

I love this website. It helped me choose the flooring for my mobile home.

I went with Bamboo

All wood flooring is a tongue & groove construction.
Solid wood is glued or nailed to the subfloor & can be refinished by sanding so therefore has a long lifespan.
Engineered floor is still solid wood on the surface but it is a thin layer of wood glued to a plywood base. It is also nailed or glued to the subfloor & is less likely to suffer from shrinkage than solid wood.. Engineered flooring generally can not be re-sanded. Floating floors r not nailed to the subfloor & therefore can be easily removed or replaced. The edges r glued together or snap together.
Laminate flooring is floating type flooring & not wood at all. it is a photograph of wood covered by a hard plastic. It is more durable than wood & is easy for do it yourselfers to install.

The differences can be viewed online in the following chart:
http://homerenovations.about.com/od/floors/a/artwoodflrchart.htm

Hardwood is considered a nicer finish, & is more expensive than laminate. I would assume (although I have not shopped for) that engineered wood fits somewhere inbetween the two in both quality & price.

Home depot & Lowes can help, but I suggest shopping around for various contractors. Ask friends or neighbors for references too. This site is helpful:
http://homerenovations.about.com/od/floors/ht/hardwoodinstall.htm

Additional information:

Engineered Flooring:
http://homerenovations.about.com/od/floors/a/artengineerflr.htm

Laminate Flooring:
http://homerenovations.about.com/od/floors/a/Artlamfloor.htm

Consumer Reports website is a great source of information for that kind of thing. You could also find good information on the Home Depot or Lowes websites. Or DIY network.