P.M. stands for "Post Meridiem," a Latin term meaning "after midday." It is used to indicate the time from noon (12:00 PM) to just before midnight (11:59 PM). This system helps distinguish between morning and afternoon/evening hours in the 12-hour clock format. In contrast to A.M. (Ante Meridiem), which refers to the time from midnight to noon, P.M. is essential for scheduling events, meetings, and activities. For example, a meeting scheduled for 3:00 P.M. occurs in the afternoon, while a breakfast meeting at 9:00 A.M. takes place in the morning.