Double-Checked Locking:?

Short answer: This is a more advanced form of lazy initialization that avoids the performance overhead of locking once the instance has been created. public class Singleton

Example code

{
private static Singleton _instance;
private static readonly object _lock = new object();
private Singleton() { }
public static Singleton Instance
{ get {
if (_instance == null)
{ lock (_lock) {
if (_instance == null)
{
_instance = new Singleton();
}
}
}
return _instance;
}
}
}

Real-world example (ShopNest)

Use a GoF pattern in ShopNest only when it removes duplication or makes a change safer—explain the problem it solves in the interview.

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.