Brealey, Principles of Corporate Finance, 13e, describes the theory and practice of corporate finance. We hardly need to explain why financial managers have to master the practical aspects of their job, but we should spell out why down-to-earth managers need to bother with theory. Throughout this book, we show how managers use financial theory to solve practical problems. Much of this book is concerned with understanding what financial managers do and why. But we also say what financial managers should do to increase company value. Some of the biggest changes in this edition were prompted by the tax changes enacted in the U.S. Tax Cuts and Jobs Act passed in December 2017. In the current edition, we have also continued to augment the international content as well as a number of chapters that have been thoroughly rewritten. For example, the material on agency issues in Chapter 12 has been substantially revised. Chapter 13 on market efficiency and behavioral finance is now fresher and more up to date. Chapter 23 on credit risk focuses more on the practical issues of forecasting default probabilities.