How do closures work in JavaScript?

Short answer: Closures work because functions remember the scope in which they were created, allowing access to outer function variables even after the outer function finishes.

Real-world example (ShopNest)

In ShopNest’s cart UI, a click handler closes over productId. Use let in loops so each button keeps the correct id.

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.