An application programming interface (API) routine that user-mode applications access through ordinary procedure calls. The code for the API routine is not included in the user?s executable image. Instead, the operating system automatically modifies the executable image to point to DLL procedures at run time.

An operating system feature that allows executable routines (generally serving a specific function or set of functions) to be stored separately as files with .dll extensions. These routines are loaded only when needed by the program that calls them. There are no glossary terms that begin with this letter. There are no glossary terms that begin with this letter.

Dynamic-link library (also written without the hyphen), or DLL, is Microsoft's implementation of the shared library concept in the Microsoft Windows and OS/2 operating systems. These libraries usually have the file extension DLL, OCX (for libraries containing Active X controls), or DRV (for legacy system drivers).