12pm is noon. 12am is midnight.

To be clear we say “noon” or “12 noon” and “midnight” or “12 midnight”. “Midday” is in the dictionary but not commonly used.

As you can see below. People have differing opinions, hence you cannot rely on these to do anything except but potentially start a heated conversation. Whatever is the "right answer" it is irrelevant if your listener does not use it. Hence as Karl suggests, if siomething is important it is often avoided. hence 0-hundred hours, 24-hundred hours, 00:00 12:00 24:00 - still 12:00 requires context, prior knowledge for interpretation. I do as Karl does, midday and midnight. For anything you read: you have to guess which camp they are in, or from context. . For myself as 11:00 is obviously AM 12:00 is obviously AM, but 12:01 is PM and since PM starts at noon. as 13:00 = 1 PM 12:00 is obviously PM . which leads me to wonder why no one ever taught one rule to rule them all and fix this.

This is confusing even for English speakers. At the Toronto film festival they never use 12AM or 12PM to announce movies. It always confuses people ! Instead they say the film will start at 11:59AM or 11:59PM. For myself, I don't overthink it. We just naturally use "noon" and "midnight" to designate these times.

12 p.m. is noon, 12 a.m. is midnight