Dot Net Assemblies Qutions

What is an assembly?
An assembly is sometimes described as a logical .EXE or .DLL, and can be an
application (with a main entry point) or a library. An assembly consists of
one or more files (dlls, exes, 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.
An important aspect of assemblies is that they are part of the identity of a
type. The identity of a type is the assembly that houses it combined with the
type name. This means, for example, that if assembly A exports a type called
T, and assembly B exports a type called T, the .NET runtime sees these as
two completely different types. Furthermore, don't get confused between
assemblies and namespaces - namespaces are merely a hierarchical way of
organising type names. To the runtime, type names are type names,
regardless of whether namespaces are used to organise the names. It's the
assembly plus the typename (regardless of whether the type name belongs
to a namespace) that uniquely indentifies a type to the runtime.
Assemblies are also important in .NET with respect to security - many of the
security restrictions are enforced at the assembly boundary.
Finally, assemblies are the unit of versioning in .NET - more on this below.