Indispensable practical tips for writing code at a sustainable pace and managing the complexity that often causes projects to spin out of control. The book describes methods and processes that allow you to solve key issues: from creating checklists to organizing teamwork, from encapsulation to decomposition, from API design to unit testing. The author illustrates his conclusions with code fragments taken from the finished project. Written in C#, they will be understandable to anyone using any object-oriented language, including Java, C++, and TypeScript. For a more in-depth study of the material, you can download all the code and detailed commit comments.