Dependency injection helps us to create reusable flexible code by making the dependencies explicit and replaceable. This talk starts by looking at how this works as a pattern, the various types of injection and how this can help us write flexible code. Whilst using a dependency injection container is not necessary to gain the benefits of dependency injection it helps to manage the dependencies in larger applications. The Symfony container is powerful and fully featured, the second part of this talk explored this container and how it can be a powerful asset in developing maintainable applications.