How do you avoid tight coupling in large .NET projects?

Short answer: Use interfaces and abstractions (DIP). Apply Dependency Injection. Modularize code into bounded contexts or separate projects. Use events or messaging for decoupled communication. Avoid static state and global variables.

Real-world example (ShopNest)

Patterns in ShopNest should solve a real pain (swappable payments, test seams)—not be added for decoration.

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.