You're here because you have a file that has a file extension ending in .ddt. Files with the file extension .ddt can only be launched by certain applications. It's possible that .ddt files are data files rather than documents or media, which means they're not meant to be viewed at all.

Game files classified as Football Manager keep player data files are saved in the DDT format, and these files are created and used by the Football Manager software. Sports Interactive developed the DDT format and append these DDT files with the .ddt extension. Sports Interactive also developed the Football Manager application as a program designed to provide a set of interactive game features for managing and organizing football teams in simulated environments and situations. Instructions and settings encoded in plain text format are stored in these DDT files by Football Manager users who authored associated game output files that correspond to certain DDT files. Football player acquisition details, or player exports and imports done in the game, comprise the data stored in these DDT files. These details saved in a DDT file are referenced by the Football Manager application to extend the functionalities integrated into the software in terms of the retention and deletion of football players in a team included in a Football Manager simulated game. Mac and Microsoft Windows users can install and use the Football Manager software to implement support for these DDT files and at the same time access the set of functionalities implemented by Sports Interactive into this video game.

Launch a .ddt file, or any other file on your PC, by double-clicking it. If your file associations are set up correctly, the application that's meant to open your .ddt file will open it. It's possible you may need to download or purchase the correct application. It's also possible that you have the correct application on your PC, but .ddt files aren't yet associated with it. In this case, when you try to open a .ddt file, you can tell Windows which application is the correct one for that file. From then on, opening a  .ddt file will open the correct application. Click here to fix .ddt file association errors

Be careful not to rename the extension on .ddt files, or any other files. This will not change the file type. Only special conversion software can change a file from one file type to another.

A file extension is the set of three or four characters at the end of a filename; in this case, .ddt. File extensions tell you what type of file it is, and tell Windows what programs can open it. Windows often associates a default program to each file extension, so that when you double-click the file, the program launches automatically. When that program is no longer on your PC, you can sometimes get an error when you try to open the associated file.