[Spring] IoC (Inversion of Control) and DI (Dependency Injection)

IoC

IoC enables a framework to take control of the flow of a program and make calls to our custom code.

decoupling the execution of a task from its implementation
making it easier to switch between different implementations
greater modularity of a program
greater ease in testing a program by isolating a component or mocking its dependencies, and allowing components to communicate through contracts