What is a cord of firewood?

And how to avoid paying too much for one.

Firewood quantities are sometimes difficult to estimate. The official measurement of firewood is a "cord". To help you make an accurate
estimate, here is how some common units of firewood measurement compare to the full cord.

A full cord is a large  amount of wood. It measures 4 feet high by 4 feet
wide by eight feet long (4'x4'x8') and has a volume of 128 cubic feet.