Article of the month June

That is easy - twenty-four hours to a day.
It sounds simple enough, but in our daily lives, we use two systems.

The first counts from 00:00 to 24:00 and starts at midnight.
We use it especially for travel by train, bus, boat and aeroplane and apply it without any hesitation.

However, we also use a system of two times twelve hours.
To discriminate between the hours before noon and those after, we add the abbreviations a.m. (ante meridiem, before noon) or p.m. (post meridiem, after noon).
We may feel that the starting points of this reckoning are midnight and noon, but the actual switch is at one o'clock.
As shown in the table below, we continue normally after twelve, and do not start over until one o'clock.
The example is for a.m. to p.m., but it is equally valid at night if you interchange the a.m. and p.m. labels.