What is C#?
Quick Answer
C# is a modern, statically typed, object-oriented (and increasingly functional) programming language from Microsoft. It compiles to Intermediate Language (IL) that runs on the .NET runtime (the CLR), which provides garbage collection, type safety and JIT compilation. It is used for web apps, APIs, desktop apps, cloud services, games (Unity) and mobile.
C# is Microsoft's main .NET language. It's statically and strongly typed and object-oriented, but it's picked up a lot of functional features over the years — LINQ, lambdas, pattern matching, records. It compiles to an intermediate language that runs on the CLR, which gives you garbage collection, type safety and JIT compilation, so you're not managing memory by hand. It's used across the board — web APIs with ASP.NET Core, desktop, cloud, and games through Unity.
Characteristics interviewers look for:
- Managed — C# compiles to IL, not native code; the CLR JIT-compiles and runs it, handling memory via the garbage collector.
- Statically & strongly typed — types are checked at compile time;
varis still static typing with inference. - Object-oriented — classes, inheritance, interfaces, encapsulation, polymorphism — plus generics.
- Multi-paradigm — LINQ, lambdas, pattern matching, records, immutability features bring a functional style.
- Type system — a unified system of value types (
struct,enum) and reference types (class,interface, delegates, arrays), all rooted atobject. - Memory safety — no manual free; the GC reclaims unreachable objects.
unsafe/pointers exist but are opt-in.
C# evolves yearly with .NET — recent additions include records, nullable reference types, pattern matching, top-level statements, and primary constructors.