Book Value is an important metric for investors because it represents the cost of carrying an asset on a company's balance sheet. It is calculated by subtracting the asset's cumulative depreciation from its original cost. As a result, book value may alternatively be thought of as a company's net asset value (NAV), which is derived by subtracting total assets from intangible assets (patents, goodwill) and liabilities. Book value may be net or gross of expenses such as trading fees, sales taxes, service charges, and so on for the initial outlay of an investment.While book value can provide useful information about a company's financial health, it should not be used in isolation to make investment decisions. Investors should also consider other factors such as earnings potential and market conditions when making decisions about whether or not to invest in a particular company.