Why do we have time zones?

Answer 1

Since the earth is a rotating globe, you can think of noontime (and midnight) as continuously appearing, infinitely many times, as the sun appears to reach its highest elevation from point to point around the world. The only people experiencing the same clock time as you would be anyone on your exact line of longitude. That's the way it was for a long time, until it became clear that a more unified approach to setting clocks made much more sense. Imagine the craziness of scheduling things like train travel (and avoiding horrible accidents at the same time) when virtually all time was locally defined. With time zones (there are 24 of them in the original concept, each 15 degrees longitude wide) it is clear what time it is anywhere in the world, provided you know the time zone and you also know whatever daylight savings rules are in effect there. There are also places that have changed the boundaries of time zones usually for good practical reasons, and there are some zones that are off-set from adjacent zones by times other than one hour. Yes, there are still complications, but it is far better than every community having its own local time.

Answer 2

We have time zones to help coordinate and standardize timekeeping across different regions of the world. Time zones allow for consistent time measurement and scheduling for activities such as travel, telecommunications, and international business. They also help to account for the Earth's rotation and the fact that daylight and darkness occur at different times in different locations.