The English-language convention I was taught is that 12am is midnight — the rationale I was given was that 02:00:00 is 2am without ambiguity, and 00:00:01 is 1

The English-language convention I was taught is that 12am is midnight — the rationale I was given was that 02:00:00 is 2am without ambiguity, and 00:00:01 is 12:00:01am without ambiguity, so 00:00:00 gets to be 12am. I have no idea if that’s a good explanation, but it helped contextualise what in the end is a convention. In my personal experience most English-speaking people will either say “midnight” or use the military convention of 00:00 or 24:00 hours. Royal Observatory Greenwich explains it succinctly[1]: > When most people say 12pm, typically they're talking about the middle of the day: 12 noon. When they say 12am, they normally mean 12 midnight. > While most people follow this convention, technically it's not quite right – as you'll see from the definition of am and pm below. To avoid any confusion (and to make sure you arrive on time), it might be best to say 12 noon or 12 midnight instead. US English is similar[2]: > The American Heritage Dictionary of the English Language (Fourth Edition, 2000) has a usage note on this topic: "Strictly speaking, 12 a.m. denotes midnight, and 12 p.m. denotes noon, but there is sufficient confusion over these uses to make it advisable to use 12 noon and 12 midnight where clarity is required." > Many U.S. style guides, and NIST's "Frequently asked questions (FAQ)" web page, recommend that it is clearest if one refers to "noon" or "12:00 noon" and "midnight" or "12:00 midnight" (rather than to "12:00 p.m." and "12:00 a.m."). Some other style guides suggest "12:00 n" for noon and "12:00 m" for midnight. [1] https://www.rmg.co.uk/stories/topics/noon-12-am-or-12-pm https://www.rmg.co.uk/stories/topics/noon-12-am-or-12-pm [2] https://english.stackexchange.com/questions/66633/is-it-correct-to-say-1200am https://english.stackexchange.com/questions/66633/is-it-corr...