Why are there different time zones all over the world? — Sam, Ozone Park, New York
The earth is divided into 24 time zones. For example, in the United States there are four time zones known as Eastern, Central, Mountain and Pacific. The time in each time zone is an hour different from the next.
We have these time zones because people like to have the sun directly overhead (or close to that) at noon. Since the earth rotates once every 24 hours, an easy way to do that is to divide the planet into 24 zones. There could have been 48 or 12, but people seem to be happy with the 24. For more info see How Time Works