Editing Delta encoding (section)

{{Short description|Type of data transmission method}}
{{Distinguish|Elias delta coding|delta modulation}}

'''Delta encoding''' is a way of storing or transmitting [[data]] in the form of ''[[Data differencing|differences]]'' (deltas) between sequential data rather than complete files; more generally this is known as [[data differencing]]. Delta encoding is sometimes called '''delta compression''', particularly where archival histories of changes are required (e.g., in [[revision control software]]).

The differences are recorded in discrete files called "deltas" or "diffs". In situations where differences are small – for example, the change of a few words in a large document or the change of a few records in a large table – delta encoding greatly reduces data redundancy. Collections of unique deltas are substantially more space-efficient than their non-encoded equivalents.

From a logical point of view, the difference between two data values is the information required to obtain one value from the other – see [[relative entropy]]. The difference between identical values (under some [[equivalence relation|equivalence]]) is often called ''0'' or the neutral element.