24-hour clock is officially called; " the international standard notion of time .
You frequently hear people refer to; " 8AM in the morning"
Is this to be sure that the other party don’t confuse it with; “8PM in the evening”?
Or is it because the speakers don’t know what AM and PM stands for themselves?
To make it even more confusing, the abbreviation used can be; PM, p.m., or (British) pm.
PS> As all Navigators know; AM = Ante Meridiem. PM = Post Meridiem (But who else care?)