The "12-Hour Format" is a way of telling time that divides the day into two 12-hour periods. The first period runs from midnight to noon, labeled as AM, while the second period runs from noon to midnight, labeled as PM. For example, 1:00 in the morning is written as 1:00 AM, and 1:00 in the afternoon is written as 1:00 PM. This format is commonly used in everyday life, especially in the United States and some other countries. It helps people easily distinguish between morning and evening times, making it simpler to schedule activities and appointments throughout the day.