DLL stand for (Dynamic Link Library) file format system which is used for holding multiple codes and procedures for Windows programs these program files were created in the DLL so we can say that multiple programs could use their information at the same time, aiding memory conservation. DLL also provide the functionality to the user to edit the coding of multiple applications at once without changing the applications themselves. The use of DLLs helps promote modularization of code, code reuse, efficient memory usage, and reduced disk space. Therefore, the operating system and the programs load faster, run faster, and take less disk space on the computer. When a program uses a DLL an issue then the program not to run and another program overwrites and breaks this dependency the original program may not successfully run.