An assembly is a collection of one or more files grouped together to form a logical unit. The term ?files? in this context generally refers to managed modules, but assemblies can include files that are not managed modules. Most assemblies contain just one file, but assemblies can and sometimes do include multiple files. All the files that make up a multifile assembly must reside in the same directory. When you use the C# compiler to produce a simple EXE, that EXE is not only a managed module, it?s an assembly. Most compilers are capable of producing managed modules that aren?t assemblies and also of adding other files to the assemblies that they create. The .NET Framework SDK also includes a tool named AL (Assembly Linker) that joins files into assemblies.