Editing Delta encoding (section)

=== Delta copying ===
''Delta copying'' is a fast way of copying a file that is partially changed, when a previous version is present on the destination location. With delta copying, only the changed part of a file is copied. It is usually used in [[backup]] or [[file copying]] software, often to save [[Bandwidth (computing)|bandwidth]] when copying between computers over a private network or the internet. One notable open-source example is [[rsync]].<ref>{{Cite web |url=http://www.2brightsparks.com/bb/viewtopic.php?t=4473 |title=Feature request: Delta copying - 2BrightSparks |access-date=2016-04-29 |archive-date=2016-03-13 |archive-url=https://web.archive.org/web/20160313021725/http://www.2brightsparks.com/bb/viewtopic.php?t=4473 |url-status=dead }}</ref><ref>{{Cite web|url=https://www.bvckup2.com/support/forum/topic/739|title = Bvckup 2 &#124; Forum &#124; How delta copying works}}</ref><ref>[http://www.eggheadcafe.com/software/aspnet/33678264/delta-copying.aspx]{{Dead link|date=July 2019 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

==== Online backup ====
{{main|Online backup services}}
Many of the [[online backup services]] adopt this methodology, often known simply as ''deltas'', in order to give their users previous versions of the same file from previous backups. This reduces associated costs, not only in the amount of data that has to be stored as differing versions (as the whole of each changed version of a file has to be offered for users to access), but also those costs in the uploading (and sometimes the downloading) of each file that has been updated (by just the smaller delta having to be used, rather than the whole file).

==== Delta updates ====
{{main|delta update}}
For large software packages, there is usually little data changed between versions. Many vendors choose to use delta transfers to save time and bandwidth.