A logbook is a record-keeping document that tracks events, tasks, or other important details in a single place. A similar term that can be used interchangeably with log book is the term journal. A journal is typically used to chronicle personal thoughts, ideas, and experiences. Another synonym for log book is ledger. A ledger is a financial tool that tracks transactions and balances. A diary is another possible synonym for log book that specifically refers to a daily record of personal experiences or events. Finally, a diary can be used to track goals, appointments, or tasks in addition to personal events.