File with an .ASD extension contains an automatically generated backup copy of a currently opened Microsoft Word document. By default it used to be saved in the C:UsersUSERNAMEAppDataRoamingMicrosoftWord directory. Files are used in order to recover lost documents and to create backup copies.

ASD files are created by an advanced text editor of the Microsoft Office package, since the 7.X version - Word. They can be opened also via program’s menu, by clicking the “open” tab and selecting “all types of files”.