How do you add elements to a List<T> in C#?

Short answer: You can use the Add() or AddRange() method.

Example code

List<int> numbers = new List<int>(); numbers.Add(10); // Add single item numbers.AddRange(new int[] { 20, 30 }); // Add 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.