Hardwood or Plywood Subfloor?
 

I am working on redecorating an upstairs bedroom. It's a half story room--nice and big, but the carpet is UGLY! I peeled up a corner, and the floor underneath it is nice and clean and not damaged...but how do I know if it is hardwood and can be refinished, or if it is the subfloor? It is in planks...

Thanks for any advice!

Hello Renee and Welcome to the Forum:
Whether you have hardwood (oak) or soft wood (pine) makes no difference; either one can be refinished. The one big problem you should look for is face nailing, if nail heads are showing they will tear a sander up and a professional won't touch it.
There are ways to tell which you have. 1. Post pictures of it as close-up as possible 2. Pine flooring is usually wider than hardwood 3. If your planks are 5-1/2" wide, its a pretty sure bet its pine.
Please let us know how it turns out.
Glenn