The word diary comes from the Latin diarium ("daily allowance," from dies "day"), found 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 of 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.
Samuel Pepys (1633-1703) is the earliest diarist who is well-known today.