# Refactoring

The third step of the "red, green, refactor" step is refactoring, the process of improving the design of existing code without altering its external behavior. It's a critical step in the process, but often overlooked. We're so passionate about refactoring, we wrote an entire book on it, Ruby Science (opens new window).

Last Updated: 11/8/2022, 7:26:39 PM