How is C# source code transformed into an executable file or bytecode?

C# source code is first compiled by a compiler (for example, csc) into an intermediate language — Microsoft Intermediate Language (MSIL), which is a platform-independent bytecode.

This MSIL along with metadata is stored in an assembly (.exe or .dll). When the program runs, the .NET runtime environment (CLR) uses Just-In-Time (JIT) compilation to convert MSIL into machine code that is understandable by the specific processor and operating system.

Thus, the transformation process looks like this:

1. C# code → compilation → MSIL (bytecode)
2. MSIL + metadata → assembly
3. At runtime → JIT compilation → machine code

This allows for portability and optimization of the code for a specific platform during execution.