INTERACTIVE .NET FUNDAMENTALS REFERENCE
Hit F5 on your fundamentals.
Polymorphism, reflection, EF internals, DI, async — the concepts under the frameworks. Every entry ships with a live, runnable demo, not just a diagram.
Pick a topic on the left, or jump straight in — every entry responds to F5
Polymorphism
Reflection
Generics
Async / Await
Entity Framework
Dependency Injection