NOTE
What Spring IoC Is
Inversion of Control and dependency injection as moving object construction/wiring policy from business classes to a container.
This is a historical learning note and may contain outdated or incomplete understanding.
Inversion of Control means application objects no longer decide all of their own construction/wiring policy. In Spring, the container creates beans and supplies their dependencies according to configuration/metadata.
Dependency injection is the main mechanism: a class declares what it needs, while composition is performed externally.
The benefit is not “no new anywhere”; it is explicit separation between object behavior and system composition/lifecycle policy.