A balance sheet term. It's what things garner at liquidation, "net of costs of selling". Caterpillar Tractor bought a smelting stove to melt iron at high temperatures. They paid $10 million for it. It should last 20 years and then they can sell it for scrap for $2 million. Using advanced calculus, we can ascertain that it will have depreciated $8 million in the 20 years that they use it. Using arithmetic depreciation, it will have declined in value $8 million / 20 = $400,000 per year in value. By year 10 of having owned the smelting stove, it will have depreciated $4 million. The book value of that stove will be held on the balance sheet of CAT as $6 million.