A logbook (or log book) is a record used to record states, events, or conditions applicable to complex machines or the personnel who operate them. Logbooks are commonly associated with the operation of aircraft, nuclear plants, particle accelerators, and ships (among other applications). The term logbook originated with the ship's log—a maritime record of important events in the management, operation, and navigation of a ship. Originally, the term "Log Book" came about in early maritime navigation. The Captain was responsible for keeping a 'Log', as a minimum, of navigational wind, speed, direction and position. The speed was determined by ejecting a 'log' from the bow of the boat and measuring the time it took to reach the stern, thereby determining the speed.