Editing Data compression (section)

=== Data differencing ===
[[File:Nubio Diff Screenshot3.png|thumb|[[File comparison|Comparison]] of two revisions of a file]]

Data compression can be viewed as a special case of [[data differencing]].<ref name="RFC 3284"/><ref name="Vdelta"/> Data differencing consists of producing a ''difference'' given a ''source'' and a ''target,'' with patching reproducing the ''target'' given a ''source'' and a ''difference.'' Since there is no separate source and target in data compression, one can consider data compression as data differencing with empty source data, the compressed file corresponding to a difference from nothing. This is the same as considering absolute [[entropy (information theory)|entropy]] (corresponding to data compression) as a special case of [[relative entropy]] (corresponding to data differencing) with no initial data.

The term ''differential compression'' is used to emphasize the data differencing connection.