What is the difference between Add() and AddRange() in a List<T>?

Short answer: Method Purpose Add() Adds one item AddRange () Adds multiple items (collection) Example: list.Add(1); // One item list.AddRange(new[] { 2, 3, 4 }); // Multiple

Example code

Method Purpose Add() Adds one item AddRange () Adds multiple items (collection) Example: list.Add(1); // One item
list.AddRange(new[] { 2, 3, 4 }); // Multiple

Real-world example (ShopNest)

In ShopNest, an order page loads products with List<Product> so you can Add items to the cart and access them by index. Use IEnumerable<T> when you only need to loop (for example, printing invoice lines).

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.