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2 File Associations

.DLL File Extension

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Dynamic Link Library Icon
File TypeDynamic Link Library
DeveloperMicrosoft
Popularity
4.4 (248 Votes) Thanks for voting!
Rare Uncommon Average Common Very Common
CategorySystem Files
File Format Description

Compiled library file containing a set of procedures and/or drivers that are referenced and executed by a Windows program; allows multiple programs to access shared system functions through common libraries; may be dynamically linked into a program at runtime.

Many DLL files are provided with the Windows operating system, and others are included by Windows programs. They allow various program functions, such as communication with external devices and hard disk input and output. They may also be referenced by Mac cross-platform applications.

NOTE: Deleting or modifying the contents of a DLL file may cause errors within the program that references the file. For this reason, DLL files generally should not be opened or edited.

Common DLL Filenames:

mfc42u.dll - A Microsoft Foundation Class (MFC) library required by some Windows programs to run. This DLL is included with Windows XP, Windows Vista, and Windows 7 and is most often located in the C:\Windows\System32\ directory. If you try to open a program and Windows reports that you're missing mfc42u.dll, likely your Windows installation has been damaged. You can use a system restore point or your factory system repair disc to fix the issue. Other related files include mfc42u.dll, mfc40.dll, and mfc40u.dll.

mfc80u.dll - An MFC library required by some Windows programs created with Visual C++ 2005. If you're missing this file, you can install the Microsoft Visual C++ 2005 Redistributable Package to install it. Programs that use this DLL generally install it because it is not included with Windows by default. Other DLLs installed with the package include msvcr80.dll, msvcm80.dll, msvcp80.dll, mfc80.dll, mfcmifc80.dll, and mfcm80.dll.

mfc90u.dll - An MFC library required by some Windows programs created with Visual C++ 2008. If you're missing this file, you can install the Microsoft Visual C++ 2008 Redistributable Package to install it. Programs that use this DLL generally install it because it is not included with Windows by default. Other DLLs installed with the package include msvcr90.dll, msvcm90.dll, msvcp90.dll, mfc90.dll, mfcmifc90.dll, and mfcm90.dll.

mfc100u.dll - An MFC library required by some Windows programs created with Visual C++ 2010. If you're missing this file, you can install the Microsoft Visual C++ 2010 Redistributable Package to install it. Programs that use this DLL generally install it because it is not included with Windows by default. Other DLLs installed with the package include msvcr100.dll, msvcm100.dll, msvcp100.dll, mfc100.dll, mfcmifc100.dll, and mfcm100.dll.

Program(s) that open .DLL files
Updated 3/27/2014

Generic Icon
File TypeDLL Dynamic Web Page
DeveloperN/A
Popularity
4.0 (42 Votes) Thanks for voting!
Rare Uncommon Average Common Very Common
CategoryWeb Files
File Format Description

Web page generated dynamically when accessed by a user; may incorporate server-side scripts, such as Perl or VB scripts that generate the HTML for the Web page.

Web pages with DLL file extensions are typically hosted on Microsoft IIS Web servers. The DLL extension must be mapped to the correct scripting engine on the server in order for the page to be processed correctly.

Program(s) that open .DLL files
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Windows
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Mac OS
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Linux
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Updated 1/21/2011