data is: Data stands for information or information set. You may open these with Microsoft Access or Visual Foxpro.
Data file means information files.
If you are looking for a file type which keeps data sets, you should make research with using database word via Google.
Database extensions may also be like these: .mdf, .dbf..
You can run these files with Microsoft Access or Visual Foxpro software.
Data File format viewers or openers
Microsoft Access, Visual Foxpro
Data File related links.