AM & PM - midnight and midday

I know exactly what you mean!

When I was a child I was told that 12 was either referred to as noon or midnight.

I always get the 2 confused! Although isn't it 00:00 for midnight?

most people use the 24 hour clock system now ,so midnight is 00.00

12 am is going into the am/morning, 12 pm is going into the pm/afternoon

Or 11.59pm is the last time in the pm, 12 is the first time in the am

it's good case for "twelve o'clock midnight" or "twelve o'clock midday". Clarity is all.

12 noon. or just noon. and midnight.. best to avoid 12 altogether.
there are arguments to shew that both am and pm are incorrect with 12, whatever the time of day. best avoid.
the person that said most people use 24 hour clock now, do they, where do you live, nobody I know does, except for technical/ job situations, eg bus/ train timetables, nurses.
I don't think most people choose the 24 hr clock for their personal life. maybe some people born outside UK do.

Reminds me, in France they use the 12 hour clock. So many of us Anglais were floored by this.
eg Votre rendevous avec le Docteur ....... est a 17 heures moins cinq.
ie a quarter to 5 pm.

Sorry, 5 to 5 pm

And in Spain, mediodía (midday) generally means the middle of the working day, so two or three o'clock in the afternoon - at least it does in the regions where I have lived and worked.
That, plus the fact that doce (twelve) and dos (two) can sound very similar in some regional accents, can easily give rise to misunderstandings when arranging meetings or appointments!

I always think of midnight as the start of the new morning so am and midday the start of the afternoon pm so in the words of the meerkats ‘simples’