AM and PM are abbreviations used to distinguish between the two 12-hour periods in a 24-hour day:
- AM stands for Ante Meridiem, which is Latin for “before midday.” It refers to the time between 12:00 midnight and 11:59 AM.
- PM stands for Post Meridiem, which is Latin for “after midday.” It refers to the time between 12:00 noon and 11:59 PM.
So, AM covers the hours from midnight to noon, and PM covers the hours from noon to midnight.