Many small farmers heat their homes with wood. It's cost efficient, especially if you can harvest your own wood from your land. But many of us have to buy wood from others.
Typically, wood is sold in units called "cords." What is a cord? Turns out, there's a standard definition for a "full cord" of wood. A full cord of wood is 4 feet wide by 4 feet high by 8 feet long.
Sometimes, people say they're selling a "cord" of wood when they mean a "face cord." A face cord is 4 feet high by 8 feet long, but its depth is the length of the firewood itself, typically 16 inches.