The word clock basically came from the Latin language word “bell” which means clocca. In past when there was no concept of clock people set out their own ways for time measurement. But those ways do not show accurate time. In ancient time’s people use to tell the time by the sun position & its movement.They have set out their own indications. Like when the sun use to be on peak they call it mid of day or noon. When the sun uses to get near the horizon, it was either sunrise or sunset. Similarly different civilizations have set their own way for time measurement. Like Hindus use to tell the time by the position of stars.

Then with the passage of time things get changed & the world first clock was invented about 14 century before. The vey first clock that was invented was called Sundial. It was named sundial because in that clock sun was use to tell time. Sundial was use for time telling around 5,500 years before. That clock was in circular disk shape and there were digits on it. The time was measured by the shadow of the sun wherever the sun shadows point on the numbered disk it shows the time. If the sun shadows lie on 9 then it means it was 9 o’clock. The big back draw of the sundial was that it works on sunlight so people can use that just in daylight.

After sundial Water clock came in use. It is named water clock because it works on water. People start using water clock around 3,400 years before. It was first invented by Egyptians but was mostly used in Greece. In water clock there were two containers marked with digit. One container is used to be placed little higher than the .And those containers were connected to each other through tube. Water use to flow from one container to another. As the water rises in the second container the float increases. And that float was connected to a stick with indicator. So as the stick raises due to high float it moves indicator which in turns moved the gear & hands point towards the time. Water clock was more precise and more in use as compare to sundial.

After sundial & water clock Pendulum came in use. In pendulum clock there use to be a pendulum with always move to & fro in result of which a wheel is turned. And those turning wheels basically move the minute & hour hands. Another type of clock in use was Quartz crystal clock. Quartz is basically glass like crystals when electricity is applied these crystals vibrate at constant rate. And due to this vibration the clock hands move.

As the earth keep on changing its position time to time that’s why in one part if its daytime then at the other ends it will be night. That’s why it was decided in 1884 to divide the earth into different zones. The earth is divided into two semicircle 7 then each semicircle is divided into 24zones.Greenwich was set as a central zone of earth.