The Price-to-Book Ratio (P/B Ratio) is a financial metric used to compare a company's market value to its book value. The market value is determined by the current stock price, while the book value is the company's total assets minus its liabilities. A P/B Ratio less than 1 may indicate that a stock is undervalued, while a ratio above 1 suggests it may be overvalued. Investors often use the P/B Ratio to assess the value of companies, especially in sectors like finance and real estate, where assets play a significant role. It helps in making informed decisions about buying or selling stocks, particularly when evaluating companies like banks or real estate investment trusts (REITs).