.NET and C# interview questions

The Common Language Runtime is the engine that loads IL, JITs it to native code, and manages memory, exceptions, and type safety.

NET Framework is the older Windows-only stack.

Intermediate Language is the CPU-independent bytecode the C# compiler emits into a DLL or EXE.

An assembly is the deployable unit, usually a DLL or EXE, plus metadata and optionally resources.

Value types like int and struct live on the stack when they are locals, and assignment copies the bits.

Boxing wraps a value type in a heap object so it can sit in an object reference.

Once created, a System.String cannot change

Const is a compile-time literal baked into callers.

Var is still statically typed

An interface is a contract of members a type must implement

Using calls Dispose at the end of the block even if an exception is thrown.

It is the pattern for deterministic cleanup of unmanaged or scarce resources.

The GC tracks reachability from roots and reclaims objects with no references.

A property is get and set methods with field-like syntax, so I can add validation later without breaking callers.

Language Integrated Query lets me filter, project, and join collections in C# instead of nested loops.

IEnumerable enumerates in the app process.

Async methods return a Task and await yields the thread until the awaited work finishes.

Task represents an asynchronous operation that will complete with a result or an exception.

Public, private, protected, internal, and protected internal are the ones I name first.