But 00:00:00 does not represent the first second of your day. It represents a _point_in time, which has no duration. The first second of your day is an interva

But 00:00:00 does not represent the first second of your day. It represents a _point_in time, which has no duration. The first second of your day is an interval between the moment your clock shows 00:00:00 and the moment it shows 00:00:01. If 00:00:00 is the fist second, why it's not the first minute and not the first hour? Is the fist second is the same as the first minute and the first second?