# Inversion of Control

By Saurabh Kumar · TIL note, Dec 22, 2025 · Tags: architecture

Source: https://saurabh-kumar.com/til/1766404800/

[Inversion of Control](https://en.wikipedia.org/wiki/Inversion_of_control) principle -- "Don't call us, we'll call you".
- This design principle is used widely in Web Frameworks, GUI programs, etc in the form of event listeners, dependency injections, callbacks to avoid boilerplate code, resuability and testability.
- Some popular examples are DOM, Flask, [NestJS](https://docs.nestjs.com/providers), Angular, etc.