Assemblies

An assembly is a collection of modules and resources that are part of the same version of an application and are deployed together; thus these items are considered to make up a single unit. The term resource refers to anything (other than code) used by an assembly. Resources can include graphical resources (such as icons, bitmap images, and so forth) or anything else that a program uses to perform its job (such as text or binary files). Simple assemblies often consist of just one file (a .NET module), whereas more complex assemblies may include numerous files (both modules and resources).

Exactly one file in the assembly ( generally a .DLL file) contains an assembly manifest that fully describes the assembly. This manifest contains its own metadata, which includes version, culture, and originator information, as well as references to and checksums of the items in the assembly. The existence of an assembly manifest is what turns a module into an assembly. Sometimes this manifest is attached to a module in an assembly; at other times a special, empty module is created solely to hold the manifest for the assembly. The assembly manifest references all other modules in the assembly, plus any other resources required by the assembly.