Yeh dil maange more (RailFans, while ending their trip) - Kirti Solanki

Sir, it's just how different people see it.
One is called clock time or ampm time: hours are between 1 and 12, but then you have to specify am or pm, to avoid ambiguity.
The other is called "military" time or 24-hour time: hours are between 0 and 24, but you don't need to specify am or pm.
We are using ampm time for...
more...

blog entries, hours are between 1 and 12, but with am/pm, so 12:30am is 12:30 after midnight, and 12:30pm is 12:30 after noon. For train timetables, we are using military time 0 - 24.
By convention we cannot use 00:42am, since that would be wrong for common time.
That is how computers see it. As a validation of the above, you can see your Windows digital clock on your own personal computer usually (at the bottom right corner). After midnight, you will see that your own PC or laptop tells you that the current time is 12:30AM, etc. It will not say 00:30AM.