Time is defined as the continued progress of existence in the past, present and future. Using the unit of time one can measure the existence of events.
The most commonly used units of time, second, minute, hour
The second (s), is the SI unit of time.
The SI unit is an international measuring device that is commonly used in technological and science study to reduce unit uncertainty.
It is necessary to have a common unit system because it allows the whole world to understand the dimensions of one set of unit systems.