All 17 Generics questions
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What problem do generics solve compared to writing a method or class that accepts 'object'? How do you declare a generic class with a type parameter, and how do you instantiate it with a specific type? What are generic constraints and why are they needed? What is covariance and contravariance in generics? Why can't you use operators like + directly on an unconstrained generic T? How do generic type constraints ('where T : ...') restrict what types can be used, and what are the common constraint kinds? How does generic type inference work when calling a generic method, and when do you need to specify the type argument explicitly? What is covariance ('out T') and contravariance ('in T') in generic interfaces, and how does IEnumerable<out T> demonstrate covariance? What are generics in C#, and what specific problems do they solve compared to writing type-specific code? How are generics implemented for value types vs reference types in the CLR?
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C# › Generics

What are generics and why use them?

Beginner

Answer

Generics let you write type-parameterised classes/methods that work with any type while keeping compile-time type safety and avoiding boxing.
public class Box<T> { public T Value { get; set; } }
var b = new Box<int> { Value = 5 };
Real-world example List<T> and Dictionary<K,V> give type-safe collections without casts.
All 17 Generics questions