Packet writing is an optical disc recording technology used to allow writeable CD and DVD media to be used in a similar manner to a floppy disk. Packet writing allows the user to access the contents of a CD-R or CD-RW disc directly through a mounted filesystem (Unix, Linux, Mac OS X) or drive letter (Windows). Without packet writing software, one would have to use regular CD mastering recording software to burn a whole disc.
Packet writing can be used both with once-writeable media such as CD-R, DVD+R and DVD-R, and also with rewriteable media such as CD-RW, DVD+RW and DVD-RW. Once-writeable media cannot however recover space once used; A deleted file does not free space on the disk, and a modified or overwritten file occupies additional space even if the file size has not increased. When the free space on a once-writeable disk is exhausted, no further update to the disk is possible. Rewriteable (RW) media can have all the files deleted on a formatted disc, or information can be overwritten. The downside is CD-RW will fade to the point it isn't readable as the re-crystalized alloy de-crystalizes. Formatted CD-RWs seem to fade out faster than unformatted CD-RWs.
Several competing and incompatible packet writing disk formats have been developed, notably those of Roxio Drag-To-Disc (formerly DirectCD), Nero AG InCD, and Sonic Solutions Drive Letter Access. Proposed standards include UDF 1.5 and Mount Rainier.

Optical disc
Optical disc image
Recorder hardware
Authoring software
Recording technologies

• Recording modes
  Packet writing
  Laserdisc
  Compact disc/CD-ROM: CD-R, CD-RW
  MiniDisc
  DVD: DVD-R, DVD-D, DVD-R DL, DVD+R,  DVD+R DL, DVD-RW, DVD+RW,  DVD-RW DL, DVD+RW DL, DVD-RAM
  Blu-ray Disc: BD-R, BD-RE
  HD DVD: HD DVD-R: HD DVD-RAM
  UDO
  UMD
  Holographic data storage
  3D optical data storage
  History of optical storage media
  Rainbow Books
  File systems
  
  
  
  • ISO 9660
    
    
    
    • Joliet
      Rock Ridge
      
      
      
      • Amiga Rock Ridge extensions
        El Torito
        Apple ISO9660 Extensions
        Universal Disk Format
        
        
        
        • Mount Rainier