What is the difference between an abstract method and a virtual method? Feature Abstract Method Virtual Method Implementatio n No implementation Has implementation Must override? Must be overridden Optional to override Class type Must be in abstract class Can be in any class Purpose Force derived classes to implement
llow derived class to optionally override
What interviewers expect
- A clear definition tied to OOP in C# OOP projects
- Trade-offs (performance, maintainability, security, cost)
- When you would and would not use it in production
Real-world example
In a production C# OOP application, teams apply this when handling user-facing features or integration boundaries. For example, you might use it during a sprint where reliability and observability matter—logging metrics, validating edge cases, and documenting the decision in an ADR so future developers understand why the approach was chosen.
How to explain in the interview
- Define the concept in one or two sentences.
- Context — where it fits in C# OOP architecture.
- Example — a specific project, bug, or performance win.
- Trade-off — what you gain vs what you sacrifice.
Tip: Practice aloud on Toolliyo mock interview or the Interview Q&A section before your real interview.