Book Value is a company's common stock equity as it appears on a balance sheet, equal to total assets minus liabilities, preferred stock, and intangible assets such as goodwill. This is how much the company would have left over in assets if it went out of business immediately. Since companies are usually expected to grow and generate more profits in the future, market capitalization is higher than book value for most companies. Since book value is a more accurate measure of valuation for companies which aren't growing quickly, book value is of more interest to value investors than growth investors.

To clearly distinguish the market price of shares from the core ownership equity or shareholders' equity, the term 'book value' is often used since it focuses on the values that have been added and subtracted in the accounting books of a business (assets - liabilities). The term is also used to distinguish between the market price of any asset and its accounting value which depends more on historical cost and depreciation. It may be used interchangeably with carrying value. While it can be used to refer to the business' total equity, it is most often used:

- as a 'per share' value': The balance sheet Equity value is divided by the number of shares outstanding at the date of the balance sheet (not the average o/s in the period).
- as a 'diluted per share value': The Equity is bumped up by the exercise price of the options, warrants or preferred shares. Then it is divided by the number of shares that has been increased by those added.

By being compared to the company's market value, the book value can indicate whether a stock is under- or overpriced.