Writeprint is a term proposed by some forensic linguistics researchers to denote a set of distinguishing stylometric characteristics of a written text (writer invariants) such as "vocabulary richness, length of sentence, use of function words, layout of paragraphs, and key words" which allow one to identify its author (if written by a single person).
It is suggested that writeprints could provide forensics experts with a new tool for identifying criminals in a digital medium, much like a digital fingerprint.
References
Writeprint Wikipedia(Text) CC BY-SA