The C# compiler compiles source code (a set of files with .cs extension) into an assembly.

• An assembly is the unit of packaging and deployment in .NET.
• An assembly can be either an application or library.
• .NET itself is a set of libraries (as well as runtime environment)

.NET 8 assemblies never have a .exe extension. The .exe after building a .NET 8 application is a platform spesific native loader responsible for starting application .dll assembly