BUP refers to two different things in the realm of the Internet and computers. First, it is a file extension for a number of different file types. Second, it is an open source freeware program for backups based on the Git packfile format, developed by Avery Pennarun beginning in December 2009 and released as of March 23, 2010 under the GNU LGPLv2 (Gnu's Not Unix Lesser General Public License version 2) license. Since it has the ability to split large files, this program makes it possible to back up very large files incrementally and it can store multiple versions without taking lots of space to do so because data is shared between incremental backups.
The file extension .BUP is used for a backup file in some, but not all cases. On a DVD, the .BUP file extension is used for a file that is the backup of the IFO or .ifo file on the DVD, which holds information like subtitles and tracks. If the IFO file is corrupted, damaged due to a scratch on the DVD, or unavailable, the BUP file will normally be used by a media player in order to play the DVD.
BUP files support a number of types of multimedia, and this is necessary for their function as a backup. In terms of video, under the ISO/IEC (International Organization for Standardization/International Electrotechnical Commisssion) standard, BUP is compatible with the various types of MPEG files, and under ITU-T (International Telecommunication Union-Telecommunication Standardization Sector), it is compatible with codecs such as H.262. BUP files support a variety of audio compression formats, including AAC (Advanced Audio Coding), MP3, and RealAudio®, and image compression formats including bmp, gif, jpg, png, and tiff. It also supports the media containers AIFF (Audio Interchange File Format) and WAV (Waveform Audio File Format), among others.
BUP was also used as the extension for backup files for file type Softcode Tracker Contact Manager backup. This program was made in Australia and is no longer available. BUP is the file extension of Brother® embroidery system files whether the embroidery system is controlled by a personal computer. It is also reportedly a file extension associated with PC-Bibliothek™ — German PC library software.
Bup also means “to quit” in Klingon.