Breakfast at 7:00 — a.m. or p.m.?
If I say 'meet me at seven o'clock,' do I mean the morning or the night? We need a way to tell them apart.
A whole day starts at midnight and ends at the next midnight. Here's the day stretched into a line.
Right in the middle is noon — twelve o'clock in the day. Noon splits the day into two halves.
The first half — from midnight up to noon — is called a.m.
The second half — from noon to the next midnight — is called p.m.
So a.m. is the morning side. Anything before noon.
And p.m. is the afternoon and evening side. Anything after noon.
We eat breakfast around seven o'clock. Which side of the day is that on?
Seven in the morning is before noon — so it lands on the a.m. side.
We write breakfast time as seven a.m.
Now dinner. Seven o'clock in the evening lands after noon — that's p.m.
A.M. is before noon, p.m. is after noon. The same number can mean two very different times of day!