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What is a Dynamic Link Library (DLL) File in Windows

You have probably encountered a DLL file in Windows if you’ve tinkered with your PC or laptop a lot. These DLL files have an extension .dll which is basically short for Dynamic Link Library and we are going to decode what exactly these files do and understand them in this article.

The use of DLLs helps promote code modularization, code reuse, efficient memory usage, and disk space reduction. Thus, the operating system and programs load faster, run faster, and take up less disk space on the computer.

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What is DLL?

As mentioned above, a DLL is short for Dynamic Link Library. It is a kind of record that contains guidelines and instructions that different applications and programs can call upon to do specific things.

Shared Libraries (also called dynamic libraries) are linked to the two-step program. First, during compilation, the linker checks that all symbols (again, functions, variables, etc.) required by the program are either linked to the program or in one of its shared libraries .

However, the dynamic library object files are not inserted into the executable file. Instead, when the program is started, a system program (called a dynamic loader) checks which shared libraries were linked to the program, loads them into memory, and attaches them to the copy of the program in memory.

Also Read: Getting Started with the Windows Subsystem for Linux

DLL File Types

There are two main types of DLL files in Windows environments, namely;

Dynamic binding at load time

In dynamic linking at load time, an application makes explicit calls to exported DLL functions like local functions.

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Dynamic binding at runtime

In run-time dynamic linking, an application calls the LoadLibrary function or the LoadLibraryEx function to load the DLL at run time.

The above files and jargon stem from the fact that DL files are natively only for Windows. The equivalents of a Windows DLL under OS X are Frameworks (Cocoa) Where dylibs (BSD). Linux has shared object (.so) files which are equivalent to DLLs on Windows. If you want to know more about these files, please see this official documentation from Microsoft itself.

Is a DLL file the same as an EXE?

DLL is basically a shared library and cannot work on its own. A .exe The file is, however, an executable which allows the DLL to run alongside and be selected along the way to provide resources for it.

It is not possible to run a DLL directly because it requires an EXE for the operating system to load through a access pointhence the existence of utilities like RUNDLL.EXE Where RUNDLL32.EXE

Due to a vulnerability commonly referred to as DLL hijacking, DLL spoofing, DLL preloading, or binary planting, many programs will load and execute a malicious DLL contained in the same folder as a data file opened by those programs. So, you must be vigilant and aware of such acts and files.


If you forget all of the above, remember that a DLL registration is a single sign-on library document. These files can be used by various projects to share functionality. A lot of people run them just expecting to fix DLL errors.

Hope you learned what is a DLL file in Windows in this article, and you can share this article widely if you enjoyed it. Chances are you won’t encounter any of these if you’re just a normal Windows user.