The programming concept that allows for code reusability is known as modularity. This approach involves breaking a program into smaller, self-contained units or modules that can be reused across different applications or parts of a project. By encapsulating functionality within modules, developers can simplify maintenance, testing, and collaboration. This not only reduces redundancy but also improves overall productivity by allowing teams to work on various components independently. Modularity is a fundamental principle in software engineering, promoting cleaner, more efficient code.