According to Universe Today, the duration of a day on Earth is the time it takes for the planet to complete a rotation around its axis. The Earth’s rotation takes 23 hours, 56 minutes and 4.1 seconds.
The other methods to measure this time are: equation, mean solar and apparent solar of time. One solar day is the time it takes for the sun to reach the highest point in relation to the sky, twice consecutively. True and apparent solar time are determined by the apparent motion of the sun on a daily basis. The lengths of solar days vary depending on the time of the year.