File Extension DLL (Dinamic Link Library)

A dynamic link library or DLL most commonly  is the term that refers to files with executable code that is loaded on demand of a program by the operating system. This title is exclusive to Windows OS being ".dll" the extension to which these files are identified, although the concept exists in virtually all modern operating systems.


DLLs are or can be seen as the evolution of static libraries (in various systems) and similarly contain functionality or resources using other applications. However, its use provides some advantages:

  • Reduce the size of executable files
  • They may be shared between several applications.
  • Facilitate the management and utilization of system memory.
  • Provide greater flexibility to changes.


However, not all are advantages. On Windows systems, the DLLs are very common and many programs use the same dynamic link libraries. But because of the evolution, each of the libraries evolves incorporating improvements but modifying them so that they are no longer compatible. This can produce two undesirable effects:

  • The installation of a program replaces a DLL with a new incompatible version.
  • The uninstalling a program delete a shared DLL.

In both cases, the result is that they stop working programs that used the old version. These problems are called the "DLL Hell". Also, please note that it is common for DLL files to contain trojans and viruses. We strongly recommend having an up-to-date antivirus software running on your PC at all times.