SOLID, Dependency Injection, and IoC Explained Across Angular, Spring, and Node.js

SOLID, Composition, Dependency Injection (DI), and Inversion of Control (IoC) are related but distinct concepts that underpin modern software frameworks like Angular, Spring, and Node.js. SOLID is a set of design principles focused on how software should be structured, while Composition refers to building larger systems by combining smaller, focused components. Dependency Injection is a technique where an object receives its dependencies from outside rather than creating them internally, promoting loose coupling. IoC takes this further by delegating the responsibility of object creation and dependency resolution to a container or framework, rather than the application code itself. Understanding how these concepts relate to each other makes it significantly easier to reason about the architectures of Angular, Spring, and Node.js applications.