Dynamically Linked Library
A dynamically linked library (DLL) is not part of an absolute file, but is linked in at load time or runtime. The primary motivation of a DLL is to allow multiple programs to share a single copy of a large library, such as X Windows. DLLs also allow a library update (e.g. security patch) to be effective for all programs without re-linking.
Ways to link in the DLL include: