What is an API key, and how do you use it in a RESTful API?

Short answer: An API key is a unique token used to authenticate requests. 👉

Example code

GET /users?apikey=12345 Best practice: Send in headers → Authorization: ApiKey 12345.

Real-world example (ShopNest)

Creating an order is POST /api/orders → 201 with Location header. Fetching is GET /api/orders/{id} → 200 or 404.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.