DelphiFAQ Home Search:
General :: Windows :: File Types
The most important file types used in Windows, Mac OS and Linux/ Unix, grouped by their extension's first letter.


This list is sorted by recent document popularity (not total page views).
New documents will first appear at the bottom.

Featured Article

File types by extension - O

These are all file name extensions starting with letter O.

  • .o   - Object file
  • .obj - Object file (Windows
  • .oca - VB cache file
  • .ocx - ActiveX control
  • .ogg - Ogg Vorbis music file
  • .old - Generic old or backup file
  • .opf - FlipBook definition fil
  • .opt - Visual studio workspace information file
  • .ost - Exchange offline storage file

Generated 4:02:09 on Jul 8, 2020