It is one day according to our clocks; it has no real significance in when compared to an actual day which is 23 hours 56 minutes 4 seconds- the time it takes the earth to make one full rotation.
Come again? If that were true, then the clock would advance past the actual time of day 2 hour for every month (30.5 days to be precise). And that would mean that in 6 months, midnight would be at high noon. So...
Indeed. But the earth is simultaneously orbiting about the Sun, which changes the apparent length of a day by approximately 3.95 minutes. (I.e., approximately 24 * 60 / 365 minutes).
Right. A sidereal day. Sorry. His point flew right over my head. I see it now.
Leap year rules have to do with the actual length of the year being 365.24219 days - not with days not being 24 hours.
The difference between solar day (about 24h+-30s) and sidereal day (about 23h56min) has nothing to do with leap years