What is the syntax to implement an interface?

Short answer: Use the colon (:) symbol and implement all members. class Car : IDriveable

Example code

{
public int Speed { get; set; }
public void Drive() => Console.WriteLine("Car is driving");
}

Real-world example (ShopNest)

Checkout calls IPaymentGateway.Charge(). Razorpay and Stripe adapters implement the same interface, so ShopNest can switch gateways without rewriting the order service.

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.