<Tr> <Td> 23: 00 </Td> <Td> 11: 00 p.m. </Td> </Tr> <Tr> <Td> 24: 00 </Td> <Td> (midnight) * (end of the day) </Td> </Tr> <Tr> <Td_colspan="3"> * See "Confusion at noon and midnight" </Td> </Tr> <P> The 24 - hour clock is the convention of time keeping in which the day runs from midnight to midnight and is divided into 24 hours, indicated by the hours passed since midnight, from 0 to 23 . This system is the most commonly used time notation in the world today, and is used by international standard ISO 8601 . </P>

Where do they use the 24 hour clock