Definition: One of more than 24 divisions of the earth, based on sections 7.5 degrees east and west of every 15 degree increment of longitude. There are 24 time zones (360 degrees divided by 15 degrees is 24) plus several offset time zones. Time zones allow the time to follow the rotation of the earth, providing a noon time at the approximate zenith of the sun in the sky of a given location.
Time Zones
By Matt Rosenberg, About.com
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