Diplomatics (in American English, and in most anglophone countries), or diplomatic (in British English), is a scholarly discipline centred on the critical analysis of documents: especially, historical documents. It focuses on the conventions, protocols and formulae that have been used by document creators, and uses these to increase understanding of the processes of document creation, of information transmission, and of the relationships between the facts which the documents purport to record and reality.
The discipline originally evolved as a tool for studying and determining the authenticity of the official charters and diplomas issued by royal and papal chanceries. It was subsequently appreciated that many of the same underlying principles could be applied to other types of official document and legal instrument, to non-official documents such as private letters, and, most recently, to the metadata of electronic records.
Diplomatics is one of the auxiliary sciences of history. It should not be confused with its sister-discipline of palaeography. In fact, its techniques have more in common with those of the literary disciplines of textual criticism and historical criticism.
Despite the verbal similarity, the discipline has nothing to do with diplomacy. Both terms are derived, by separate linguistic development, from the word diploma, which originally referred to a folded piece of writing material—and thus both to the materials which are the focus of study in diplomatics, and to accreditation papers carried by diplomats.
The word diplomatics was effectively coined by the Benedictine monk Jean Mabillon, who in 1681 published his treatise, De re diplomatica (Latin: roughly, "The Study of Documents"). From there, the word entered the French language as diplomatique, and then English as diplomatic or diplomatics.
Webster's Dictionary (1828) defines diplomatics as the "science of diplomas, or of ancient writings, literary and public documents, letters, decrees, charters, codicils, etc.