What is the difference between DIP and dependency injection containers?

DIP is the design principle (high-level modules depend on abstractions), while Dependency Injection is the pattern to achieve it, and a DI Container (IoC Container) is a framework tool that automates the injection. You can practice DIP and DI without a container by manually passing dependencies through constructors. Containers add automatic dependency resolution: you register bindings (bind(DatabaseInterface::class, MySQLDatabase::class)), and the container resolves the full dependency graph automatically when you resolve a service. Laravel's service container, Spring's ApplicationContext, and NestJS's IoC module are examples. Containers also manage lifecycle (singleton vs. transient instances) and handle circular dependency detection.