**"Refactoring. Why?"** is a book written by Martin Fowler, which is considered the bible of programmers and web developers around the world. The book describes in detail the process of refactoring - a method that consists in improving the structure of the code without changing the external functionality. The author explains why refactoring is an important component of software development and how it helps avoid the accumulation of technical debt. In the book "Refactoring. Why?" you will find not only the theoretical foundations of refactoring, but also concrete methods and approaches to improve code. The author gives many examples of real situations from his experience, which makes the material easy to understand and implement in practice. The book "Refactoring. Why?" will be a great help for every programmer who wants to improve the quality of his code, make it more understandable and easy to maintain in the future.