What is Node.js?
Why Interviewers Ask This
Foundational questions like this help interviewers calibrate the rest of the interview. A confident, accurate answer signals that you have solid Node.js basics — a prerequisite for any developer role.
Answer
Node.js is an open-source, cross-platform JavaScript runtime environment built on Chrome's V8 JavaScript engine. It allows developers to execute JavaScript code on the server side — outside of a browser. Node.js was created by Ryan Dahl in 2009 and introduced a non-blocking, event-driven I/O model that makes it lightweight and efficient for building scalable network applications. Before Node.js, JavaScript was confined to the browser; Node.js brought JavaScript to the backend, enabling full-stack development with a single language. Node.js uses an event loop and asynchronous APIs to handle many concurrent connections without the overhead of threads. It is widely used for building REST APIs, real-time applications (chat, gaming), microservices, CLI tools, and streaming applications.
Pro Tip
If you're unsure about a detail, say so honestly and explain your reasoning. Interviewers respect candidates who can think through uncertainty rather than bluffing.