Learn why experienced C# developers choose interfaces over abstract classes 95% of the time. Real-world examples, team benefits, and clean architecture tips.
A practical guide to C# Default Interface Methods: how to use them, when to avoid them, and how they help you build future-proof APIs.
Quick Reference Table Feature Abstract Class Interface When to Use Inheritance Single only Multiple allowed Abstract: shared logic; Interface: contracts Implementation Can provide Contract only Abstract: code reuse; Interface: flexibility Constructors Supported Not allowed Abstract: initialization; Interface: pure contracts State/Fields Yes No Abstract: data sharing; Interface: behavior only Performance Slightly faster Virtual dispatch Abstract: hot paths; Interface: most scenarios Testing Can be difficult Easy with mocks Abstract: integration tests; Interface: unit tests Common Pitfalls: ...