A critical characteristic of good software design is modularity. Modularity refers to the practice of breaking a software system into smaller, manageable, and interchangeable components or modules. This approach allows for easier maintenance, testing, and scaling of software applications. Well-designed modular systems enable developers to work on individual components independently, facilitating parallel development and reducing the risk of bugs. Moreover, modularity enhances code reusability and improves the overall organization of the software, leading to a more efficient development process.