PM meaning in Time ?

The 12-hour clock is a time convention in which the 24 hours of the day are divided into two periods: a.m. (from Latin ante meridiem, translating to "before midday") and p.m. (from Latin post meridiem, translating to "after midday"). Each period consists of 12 hours numbered: 12 (acting as 0), 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11.

The daily cycle starts at 12 midnight (usually indicated as 12:00 a.m.), runs through 12 noon (usually indicated as 12:00 p.m.), and continues until just before midnight at the end of the day. The 12-hour clock was developed from the second millennium BC and reached its modern form in the 16th century AD.

The 12-hour time convention is common in several English-speaking nations and former British colonies, as well as a few other countries. It is an example of a duodecimal system.