Dependency Injection is a powerful technique that is used to increase the flexibility of software applications. It is a process of supplying a class with the objects it requires, rather than having the class create or locate these objects itself. This makes the code more maintainable and easier to modify, as different objects can be injected into the class as needed. Furthermore, it allows for better testability as objects can be easily mocked or stubbed out for testing. All in all, Dependency Injection is a great tool for software developers who are looking to increase the maintainability and testability of their applications.