A.M. stands for “ante meridiem,” which is Latin for “before noon.” P.M. stands for “post meridiem,” which is Latin for “after noon.” These terms are used to distinguish between the periods of time before noon and after noon. For example, 10:00 A.M. is 10 o’clock in the morning, and 10:00 P.M. is 10 o’clock at night. The 24-hour clock, which is used in some countries, does not use A.M. or P.M. Instead, it divides the day into 24 equal hours, with 00:00 being midnight and 12:00 being noon.
