The difference between the 12-hour clock and the 24-hour clock is just a difference in expression as both are time conventions with the former dividing the day into two periods and the latter counting the full 24 hours of the day continuously. Basically, the two-time conventions are used interchangeably with some regions of the world using both of them and others prefer one over the other.

　　

The 12-Hour Clock

The 12-hour clock, which divides the day into two cycles, is mostly used in countries where English is the main language, you will still find it in use in several other countries. The time counting methodology has two equal periods of 12 hours, from midnight, denoted 12:00 a.m.(ante meridiem), to midday, denoted 12:00 p.m.(post meridiem), and from midday back to midnight, completing a full 24-hour cycle. The numbering runs from one to twelve in each period, with twelve representing zero as the starting point. The basis of counting with the 12-hour clock is the normal night and day version where the day consists of twelve hours characterized by the sun, and the night consists of twelve hours characterized by the moon. The majority of analog clocks and watches in use today use the 12-hour clock. Phrases of referring to time periods where the 12-hour clock is common include night time, morning time, afternoon time, and evening time.

　　

The 24-Hour Clock

Basing its origins in ancient Egypt, the 24-hour clock has been used for centuries and will more than likely continue to be used for years to come. The 24 hour clock time convention runs the day from midnight to midnight for a period of twenty-four hours continuously. It is the most preferred time system in the world today, with many of the regions that have adopted the 12-hour clock using it concurrently as it is recommended by international standards. The time counting system has the start of the day at midnight, denoted 00:00, which the runs through to twenty-three fifty-nine. Most computers by default reflect the time in 24-hour formats, and it is also the most preferred time methodology of many militaries. Unlike the 12-hour clock, the 24-hour clock is viewed as being specific to timelines and being easy to interpret for most people. Medics throughout the world have preferred the 24-hour clock in recording patients history, as they argue that a difference in interpretation of time would make a significant difference in a patient’s treatment. If a different medical staff were to confuse the recorded time recorded and administer medicine to a patient at the wrong time, the resultant outcome could be fatal.