''For other uses of the term 'diary', see Diary (disambiguation).

A diary is a record (originally in written book format) with discrete entries arranged by date reporting on what has happened over the course of a day or other period. Diaries undertaken for institutional purposes play a role in many aspects of human civilization, including government records (e.g., Hansard), business ledgers and military records. Schools or parents may teach or require children to keep diaries in order to encourage the expression of feelings and to promote thought.

Generally the term is today employed for personal diaries, in which the writer may detail more personal information and normally intended to remain private or to have a limited circulation amongst friends or relatives. The word "journal" may be sometimes used for "diary," but generally one writes daily in a diary, whereas journal-writing can be less frequent.

Whilst a diary may provide information for a memoir, autobiography or biography, it is generally written not with the intention of being published as it stands, but for the author's own use. In recent years however there is internal evidence in some diaries (e.g., those of Alan Clark, Tony Benn or Simon Gray) that they are written with eventual publication in mind, with the intention of self-vindication (pre- or posthumous) or simply for profitFact: date=February 2009.

Diaries are highly varied, from business notations, to listings of weather and daily personal events, to inner explorations of the human psyche, to expressions of one's deepest self to records of thoughts and ideas.

By extension the term diary is also used to mean a printed publication of a written diary; and may also refer to other terms of journal including electronic formats (e.g., blogs).

History

The word diary comes from the Latin '' ("daily allowance," from dies "day," more often in the plural form diaria). The word journal comes from the same root (diurnus "of the day") through Old French jurnal (modern French for day is jour'').

Until around the turn of the 20th century, with the worldwide rise of literacy, diary writing was generally a practice of the members of the middle and upper classes.

The oldest extant diaries come from Middle Eastern and East Asian cultures, although the even earlier work To Myself (Τὰ εἰς ἑαυτόν), written in Greek by the Roman Emperor Marcus Aurelius in the second half of the 2nd century AD, already displays many characteristics of a diary. Pillowbooks of Japanese court ladies and Asian travel journals offer some aspects this genre of writing, although they rarely consist exclusively of diurnal records. The scholar Li Ao (9th century AD), for example, kept a diary of his journey through southern China.

In the medieval Near East, Arabic diaries were written from before the 10th century, though the surviving diary of this era which most resembles the modern diary was that of Ibn Banna in the 11th century. His diary is the earliest known to be arranged in order of date (ta'rikh in Arabic), very much like modern diaries.