In any enterprise application, coordination between the working objects is very important for a business goal. The relationship between objects in an application represents the dependency of an object, so each object would get the job done with coordination of the dependent objects in the application. Such required dependencies between the objects tend to be complicated and with tight-coupled programming in the application. Spring provides a solution to the tight-coupling code of an application by using the dependency injection pattern. Dependency injection is a design pattern, which promotes the loosely coupled classes in the application. This means that the classes in the system depend on the behavior of others, and do not depend on instantiation of object of the classes. The dependency injection pattern also promotes programming to interface instead of programming to implementation. Object dependencies should be on an interface, and not on concrete classes, because a loosely coupled structure offers you greater reusability, maintainability, and testability.