Node.js
In plain terms
A runtime for executing JavaScript outside the browser.
Going deeper
Node.js runs JavaScript on the server using an event-driven, non-blocking model, ideal for scalable I/O-heavy apps. It unified frontend and backend languages.
Under the hood
Single-threaded event loop excels at concurrency for I/O but not CPU-bound work; huge npm ecosystem.
Examples
APIs, real-time apps, tooling, Express servers, build tools.
Think of it like...
Like letting the browser's engine power your kitchen, not just your dining room.