AM and PM are abbreviations for “ante meridiem” and “post meridiem,” respectively. These terms are used to indicate the time of day, with AM referring to the time before noon and PM referring to the time after noon.
AM and PM are commonly used in standard time and in military time. Standard time is the time that is used in most countries and regions, and it is based on a 12-hour clock. In standard time, the hours between 12:00 AM and 11:59 AM are considered to be in the AM, and the hours between 12:00 PM and 11:59 PM are considered to be in the PM.
On the other hand, Military time is the time system used by the military, as well as by some other groups, such as pilots, air traffic controllers, and emergency services. Military time uses a 24-hour clock, and it is based on the number of hours that have passed since the start of the day. For example, 00:00 hours is the start of the day, while 23:59 hours is the end of the day.
Overall, the usage of AM and PM is a simple way of distinguishing between the hours that occur before and after noon. This helps people to easily understand and communicate the time of day, whether they are referring to a specific point in time or a general time period.