What is a Assembly

1. Assembly is unit of deployment like EXE or a DLL.

2. An assembly consists of one or more files (dlls, exe’s, html files etc.), and
represents a group of resources, type definitions, and implementations of those
types. An assembly may also contain references to other assemblies. These
resources, types and references are described in a block of data called a manifest.
The manifest is part of the assembly, thus making the assembly self-describing.

3. An assembly is completely self-describing.An assembly contains metadata
information, which is used by the CLR for everything from type checking and
security to actually invoking the components methods.As all information is in
assembly itself it is independent of registry.This is the basic advantage as
compared to COM where the version was stored in registry.

4. Multiple versions can be deployed side by side in different folders. These
different versions can execute at the same time without interfering with each
other.Assemblies can be private or shared. For private assembly deployment,the
assembly is copied to the same directory as the client program that references
it.No registration is needed, and no fancy installation program is required.
When the component is removed, no registry cleanup is needed,and no uninstall
program is required. Just delete it from the hard drive.

5. In shared assembly deployment, an assembly is installed in the Global Assembly
Cache (or GAC). The GAC contains shared assemblies that are
globally accessible to all .NET applications on the machine.