What is dll?

What is dll?what is dll

What is dll? The dll is an abbreviation of the term Dynamic Link Library, but still for you this term isn’t an answer for the question of “what is dll”, so I will describe briefly and will make it clearer below.

To have an idea of what is dll, you have to understand that a DLL also a library that contains code and data which can be used by more than one program at the same time, hence, a DLL controlling and facilitating the operations for any Microsoft Windows based program, and for an example there are programs which may contain many different modules and each of those modules of the same program contained and distributed via DLLs.

Generally, DLLs are represented by files with the extension of “.dll” at the end of the file name, but some DLL files are used in several different file extensions as the DLL functionality located within its code.

What is DLL advantage

Understanding what is dll from above isn’t enough to get the full picture of it, there are many benefits and advantages behind using the DLLs in programs or within Microsoft Operating Systems which makes you realize more what is dll:

  • DLL helps promote modularization of code. (Each module of a code uses a DLL to function).
  • DLL helps code reuse.
  • DLL helps making efficient usage of the memory. (By using fewer resources as many programs may use the same DLLs).
  • DLL reduces disk space.
  • DLL makes the Operating System load and run faster.
  • DLL make programs load and run faster.
  • Updating programs are easier using DLLs.

[scheaven_infobox color=”grey” width=”100″ align=”none” icon=”info2″]Note: Program updates are easier to apply to each module without affecting other parts of the program; hence you can apply an update without needing to install the whole program again.[infoclose color=”grey”]

What is DLL risk

The risk behind DLLs is all about being used by malicious software or virus which is called DLL Hijacking, this happened by a malicious code injected into an application via a malicious DLL with the same name as a DLL used by the application, and that’s why Windows File Protection implemented (you will read about it below).

One of the solution to solve such issues by running an updated antivirus software in safe mode and scan for viruses.

[scheaven_infobox color=”grey” width=”100″ align=”none” icon=”info2″]Note: Correct deep steps on how to clean you Windows from viruses from my other article How to clean my PC from Viruses?.[infoclose color=”grey”]

What is DLL problem

To have a full understanding of what is dll, you need to understand the dll problems and solutions, many programs issues cause by the DLLs, and especially for those programs or tools that do not run when you try to execute them while getting an error message of a corrupted or missing dll files, and off course this caused by an issue called dependency.

I will simplify it more, when a program uses a DLL, a dependency is created, if another program overwrites and/or breaks this dependency, the original program may not successfully run and you will get the error message or dialogue box, these actions are known as DLL conflicts.

what is dll issue troubleshooting

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 i.e.: If one of the following actions occurs:


  • A dependent DLL is upgraded to a new version.
  • A dependent DLL is fixed.
  • A dependent DLL is overwritten with an earlier version.
  • A dependent DLL is removed from the computer.
 any program may not run

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How to deal with DLLs problems or issues and DLL troubleshooting?

Now, I can categorize the answer for this question into two categories, the prevention and protection, and the second is manual troubleshooting.

DLL issues Prevention and Protection:

Microsoft has made a protection for DLLs in their Operating Systems to minimize the dependency issues in two ways:

  1. Windows File Protection: The Microsoft Operating System is preventing DLLs from being updated or deleted by any unauthorized third parity agent, hence when DLL modification requested by a third parity program (i.e. software installation), Windows File Protection will look for a valid digital signature to allow the installation process.
  2. Private DLLs: By using the Private DLLs, the program will be isolated from changes that are made to shared DLLs. Private DLLs use version-specific information to enforce the version of the DLL that is used by the program in the program root folder

DLL issues manual troubleshooting:

There are a couple of tools that you may use to solve and troubleshoot DLL issues:

1. Dependency Walker: A tool where you use to open your defected program and check its DLLs for:

  • Missing DLLs.
  • Program files or DLLs that are not valid.
  • Import functions and export functions match.
  • DLLs Circular dependency errors.
  • Modules that are not valid for a different operating system.

[scheaven_infobox color=”grey” width=”100″ align=”none” icon=”info2″]Note:Using Dependency Walker tool, you can document all the DLLs that a program uses. This may help prevent and correct DLL problems that may occur in the future.[infoclose color=”grey”]

To download Dependency Walker tool and read more about how to use it from the below button:

[scheaven_button color=”blue” icon=”down” link=”https://www.dependencywalker.com/” text=”Dependency Walker Download”]

Dependency Walker Download

2. DLL Universal Problem Solver DUPSThe DLL Universal Problem Solver (DUPS) tool used to compare, audit, document, and display DLL information such as the below utilities that DUPS tool uses:

  • Dlister.exe: This utility enumerates all the DLLs on the computer and logs the information to a single text file or a database file.
  • Dcomp.exe: This utility compares the DLLs that are listed in two text files and produces a third one that display the differences.
  • Dtxt2DB.exe: This utility loads the text files that are created by using the Dlister.exe utility and the Dcomp.exe utility into the dllHell database.
  • DlgDtxt2DB.exe: This utility provides (GUI) a graphical user interface of Dtxt2DB.exe.

To download and learn how to use the DLL Universal Problem Solver (DUPS) tool from Microsoft via the below button:

[scheaven_button color=”blue” icon=”down” link=”https://support.microsoft.com/kb/247957″ text=”DLL Universal Problem Solver (DUPS) Download”] [scheaven_infobox color=”red” width=”100″ align=”none” icon=”0″]If you find this article useful please share it from the facebook button below or other social buttons.[infoclose color=”red”]

Hope you had an answer for your question of What is dll, don’t hesitate to leave a comment below.

Firas Sameer

This is me Firas Sameer the founder of Dealing With Windows, I am a computer and telecommunication engineer with over 14 years of experience, I love helping people and I love spending some of my free time posting useful articles for free about Microsoft windows.

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