A diary is a written or record with discrete entries arranged by date reporting on what has happened over the course of a day or other period.
Diaries have traditionally been handwritten . A personal diary may include a person’s experiences, thoughts, and/or feelings, excluding comments on current events outside the writer’s direct experience.

Someone who keeps a diary is known as a diarist. 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, the word may also denote a preprinted journal format.

Today the term is generally employed for personal diaries, normally intended to remain private or to have a limited circulation amongst friends or relatives.