What is the difference between generic and non-generic collections in C#?

Short answer: Generic collections are type-safe and defined using generics (<T>), allowing you to specify the type of elements they hold.

Explain a bit more

This ensures compile-time type checking and eliminates the need for casting. Non-generic collections, on the other hand, store elements as objects (object type), requiring boxing/unboxing for value types and casting for reference types. Example: // Generic collection List<int> numbers = new List<int>(); numbers.Add(10); // No boxing, type-safe // Non-generic collection ArrayList list = new ArrayList(); int value = (int)list[0]; // Needs casting Real-world use case: In applications dealing with specific data types (e.g., a list of customer IDs), generic collections are ideal. Non-generic collections may be used in legacy systems or when dealing with multiple data types.

Example code

list.Add(10); // Boxing occurs

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.