What is time?Time is a measurable period during which an action, process, or condition exists or continues. It is often referred to as the fourth dimension, along with the three spatial dimensions. Time as a unit is any particular time interval, used as a standard way of measuring or expressing duration.
InputHour is a unit of time conventionally known as 1/24 of a day. Since it varies between seasons, it is made constant by defining it to be equal to 3600 atomic seconds.
Day is approximately the period of time during which the Earth completes one rotation around its axis.