what's the meaning of am & pm on time
12-hour clock The 12-hour clock is a time convention in which the 24 hours of the day are divided into two periods:[1] a.m. (from the Latin, ante meridiem, meaning before midday) and p.m. (post meridiem, meaning past midday).[2] Each period consists of 12 hours numbered: 12 (acting as zero),[3] 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, and 11. The 24 hour/day cycle starts at 12 midnight (often indicated as 12 a.m.), runs through 12 noon (often indicated as 12 p.m.), and continues to the midnight at the end of the day. The 12-hour clock was developed over time from the mid-second millennium BC to the 16th century AD.
Coordinated Universal Time For most common and legal-trade purposes, the fractional second difference between UTC and UT (GMT) is inconsequentially small. Greenwich Mean Time is the legal standard in Britain during the winter, and this notation is familiar to and used by the population.[21]