MD0 is a binary format used for storage of duplicated track information from a CD or DVD media device. Although MD0 files usually contain a complete duplicate of the CD or DVD that it was created from, it may also be part of a series of duplicate files and, therefore, may contain only part of the duplicate. Because of this, it is often saved with an MDF file that gives the opening program information about the files that were part of the copy and the tracks and data contained in those files.