Dependency Injection (DI) is one of the most important concepts in Angular. If you understand Angular DI deeply, you understand much more than how to inject a service into a component. You understand how Angular creates objects, controls their lifetime, chooses implementations, scopes dependenc...
Source: [Dev.to](https://dev.to/abanoubkerols/dependency-injection-in-angular-from-constructor-injection-to-modern-di-3mac)