Pre-historic man did not have a need for clocks, but as civilization evolved, that all chnaged. The historical record reveals that approximatley 5000 to 6000 years ago great civilizations in the Middle East and North Africa began to make clocks to augment their calendars. With their attendant bureaucracies, formal religions, and other burgeoning societal activities, these cultures apparently found a need to organize their time more efficiently.
A clock (from the Latin cloca - bell) is an instrument for measuring time and for measuring time intervals of less than a day - as opposed to a calendar. Those used for technical purposes, of very high accuracy, are usually called chronometers. A portable clock is called a watch. The clock in its most common modern form (in use since at least the 14th century) displays the hours, minutes and, sometimes, seconds that pass during a twelve- or twenty-four-hour period.