Glad you asked...
A cord of firewood is 4 feet high by 4 feet wide and 8 feet long. Most wood burning stoves and furnaces are shorter than 4 feet so you will rarely see a cord of firewood for sale. Most dealers will cut the cords in order to make the wood shorter for customer use. You can find more information here:
http://www.woodheat.org/firewood/cord.ht...