The ancient Egyptians are credited with dividing the day into 24 hours.
Their system was based on the observation of the stars and the movement of the sun. They divided the night into 12 hours, marked by the rising and setting of specific stars. They then divided the day into 12 hours, based on the sun's position in the sky.
This system of 24 hours was later adopted by the Greeks and Romans, and eventually spread throughout the world.
The ancient Egyptians' system was not as precise as modern timekeeping, but it was a significant step in the development of our current system of measuring time.
