Dynamic-link library (also written unhyphenated), 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
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.