Assembly Versioning
Another great advantage to using assemblies is built-in versioning-specifically, the end of "DLL hell." "DLL hell" refers to the situation in which one application overwrites a DLL needed by another application, usually with an earlier version of the same DLL, breaking the first application. Although the Win32 resource file format does allow for a versioning resource type, the operating system doesn't enforce any versioning rules so that dependant applications will continue to function. This is solely the responsibility of application programmers.
As a means of addressing this issue, the manifest includes versioning information for the assembly as well as a list of all referenced assemblies and the versioning information for those assemblies. Because of this architecture, the .NET runtime can ensure that versioning policies are upheld and applications will continue to function even when newer, incompatible versions of shared DLLs are installed on the system. Because versioning is one of the biggest benefits of assemblies, it's covered in depth, including several examples, in "Versioning Assemblies." -