What is duck typing and does C# support it with interfaces?

Short answer: Duck typing: "If it looks like a duck and quacks like a duck, it is a duck." Behavior is based on method/property availability, not type inheritance. C# does not support full dynamic duck typing, but interfaces enable a similar concept by relying on contract-based behavior. Dynamic types in C# (dynamic) can also simulate duck typing. interface IFlyable { void Fly(); }

Example code

void MakeItFly(IFlyable obj) => obj.Fly(); // Any object implementing IFlyable works

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.