Concrete Products (FileLogger and ConsoleLogger):?

Short answer: These classes implement the ILogger interface, defining how the messages are logged (either to a file or the console). FileLogger: public class FileLogger : ILogger

Example code

{
public void Log(string message) => Console.WriteLine($"Logging to file: {message}"); } ConsoleLogger: public class ConsoleLogger : ILogger
{
public void Log(string message) => Console.WriteLine($"Logging to console: {message}"); }

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.