A collection of small programs, any of which can be called when needed by a larger program that is running in the computer. The small program that lets the larger program communicate with a specific device such as a printer or scanner is often packaged as a DLL program (usually referred to as a DLL file).
Dynamic-link library (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 ActiveX controls), or DRV
(for legacy system drivers).
The file formats for DLLs are the same as for Windows EXE files – that is, Portable Executable (PE) for 32-bit and 64-bit Windows, and New Executable (NE) for 16-bit Windows. As with EXEs, DLLs can contain code, data, and resources, in any combination.
Filename extension |
.dll |
---|---|
Internet media type |
application/vnd.microsoft.portable-executable |
Uniform Type Identifier (UTI) | com.microsoft.windows-dynamic-link-library |
Magic number | MZ |
Developed by | Microsoft |
Container for | Shared library |
Data files with the same file format as a DLL, but with different file extensions and possibly containing only resource sections, can be called resource DLLs. Examples of such DLLs include icon libraries, sometimes having the extension ICL
, and font files, having the extensions FON
and FOT
.