12 pm, 12 am.

[GrannyHaddock]

What is meant by this? 12 o'clock can only be noon or midnight. I see it frequently, where hours of business etc. are listed.

12pm=12noon
12am=midnight

24 hour clock is 00:00 or 12:00 but 12 hour clock, you need to specify am or pm.

I'm a nurse and always document in 24 hour clock but day to day I use am and pm.

There’s no such time as 12pm or 12am! P.M. means ‘post-meridiem’, and 12 is on the meridiem. It’s a common misunderstanding that I find very annoying! Even the BBC use it now though

I refer to "12 noon" in written letters. I never need to refer to midnight but I would say this rather than "12pm".

My inner pedant wants to be BFF with @FaithInfinity

Ooh friend honestly I remember learning about this at school when I was 9. It bothers me more than I can say.
Also while I’m here it’s railway station not train station!

And anyway 12am should be an hour after 11am, and 12pm an hour after 11pm... People should best just say noon and midnight.

Technically, 12am would be literally one nanosecond after midnight had struck but would still be considered just 12. The same for noon. Time is always counting.

12am is just before 1am. 12pm is just before 1pm.

But yes, it should be noon and midnight.