Arrays, Span<T> & Memory<T> Asynchronous Programming Attributes & Reflection Collections Delegates, Events & Lambdas Dependency Injection & IoC Principles Design Patterns in C# Enums & Flags Equality: Equals, GetHashCode & IEquatable Exception Handling Extension Methods File I/O & Streams Fundamentals Generics Indexers & Operator Overloading Interfaces & Abstract Classes Iterators & yield return LINQ Memory & Garbage Collection Modern C# Features (Global Usings, File-Scoped Namespaces, Top-Level Statements) Multithreading & Task Parallel Library Nullable Reference Types Nullable Value Types (Nullable<T>) OOP Records & Pattern Matching Regular Expressions in C# Serialization (System.Text.Json) String Handling & StringBuilder Structs, Boxing & Unboxing Tuples & Deconstruction Unit Testing (xUnit/NUnit/MSTest) Value vs Reference Types