Code reusability refers to the practice of using existing code for new projects instead of writing new code from scratch. This approach saves time and effort, as developers can leverage previously tested and proven code components. It also helps maintain consistency across different applications, reducing the likelihood of errors. By promoting modular programming, code reusability encourages the creation of small, self-contained units of code, known as functions or modules. These can be easily shared and integrated into various programs, enhancing collaboration among developers and improving overall software quality.