Compiled set of procedures and/or drivers referenced by a software program; allows the application to access system functions and communicate with a printer or other peripheral devices.

Many DLL files are included with the Windows operating system, while others are often installed with Windows programs; modifying the contents of a DLL file may cause errors within the program that references the file; therefore, it is wise not to open or edit DLL files.

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.