AM PM - Ante Meridiem and Post Meridiem in Clock Time

AM and PM are the symbols used in the 12-hour clock system to distinguish time between day and night. The new date starts at 12:00 am in the night and ends at 11:59 am in the day (noon) after which it’s 12:00pm till 11:59 pm in the night. AM means ‘ante meridiem’ which means transition of time from night to day and pm is used to refer to the time transition from day to night. PM means ‘post meridiem’ which means ‘after noon’ and is used to refer to the time from noon till just before midnight.

AM and PM are not exact divisions of day and night. AM begins in the night and remains till noon in the day. Similarly, PM starts at noon in day time and continues till midnight. The symbols of AM and PM are based on 12hour clock design to understand the 24 hours in two parts as per clock.

S.No.	12-hour format	24-hour format	Time of day
1	6:00 AM	06:00	Early morning
2	9:00 AM	09:00	Morning
3	12:00 PM	12:00	Noon
4	4:00 PM	16:00	Late afternoon
5	11:00 PM	23:00	Night

• In ancient times, human beings have used the motion of the sun, moon, and stars to measure time for many centuries past. Early civilizations divided the day into day and night but later on used more precise methods of measuring time.
• The term ‘meridian’ relates to an imaginary line which usually denotes the highest or maximum height of the sun which is the local noon.
• The mechanical clocks were becoming more common in Europe during the middle ages and the early modern period. The utilization of a 12-hour dial became prevalent due to its simplicity compared to the 24-hour dial.
• In order to differentiate between these two 12-hour clock cycles, the terms AM and PM were introduced for its use in Northern Europe and slowly became standardized across many English-speaking communities.
• With the industrialization, railroads, and coordinated schedules, the need for a common language related to a common time became important. The AM and PM system continued to exist with the 24-hour clock which is used in many technical and military situations.
• Currently, the AM and PM system is commonly utilized in the 12-hour clock system, whereas the 24-hour system exists globally.

S.No.	Country	Time Zone	Exact Time	Time difference with reference to India
1	India	UTC + 5:30 IST	10:00 AM	-
2	United Kingdom	UTC + 0 GMT	4:30 am	India is 5 hours 30 minutes ahead in winter and 4h 30m ahead in summer. (from United Kingdom)
3	United States (New York)	UTC - 5:00 EST	11:30 pm (previous day)	India is 10h 30m ahead in winter and 9h 30m ahead in summer. (from USA)
4	Japan	UTC + 9:00 JST	1:30 pm	Japan is 3h 30m ahead of India. (from Japan)
5	Australia (Sydney)	UTC + 10:00 AEST	2:30 pm	Sydney is 4h 30m ahead of India in standard time and 5h 30m ahead in daylight time. (from Australia)
6	United Arab Emirates (Dubai)	UTC + 4 GST	8:30 am	India is 1h 30m ahead of Dubai. (from UAE)

• AM and PM provide us a very convenient way to indicate civil time according to the 12-hour clock. It eliminates the potential for confusion in the morning or evening. The lack of AM and PM would mean that we wouldn’t be sure whether it is 7:00 in the morning or 7:00 in the evening. It would cause difficulties with scheduling our activities.
• The AM has connections with sleep, early morning activities, school, work and anything that is done ‘before noon’. The PM is connected to work in the afternoon, leisure time, and evening events.
• The concept of AM and PM facilitates structuring one’s life around these activities. AM and PM can be seen in timetables, schedules, digital interfaces, and conversations.
• The AM and PM system is used alongside the 24-hour clock. It is used by preference in aviation, military activities, railways, and international affairs.
• In many cultures, the AM and PM system is still predominant as a time notation in daily life.

What is the full form of AM and PM?

The full form of AM and PM is Ante Meridiem and Post Meridiem.

What is the meaning of AM and PM?

The Ante Meridiem means before mid-day and post meridiem means after midday.