Time zones are regions of the Earth that share the same standard time. The world is divided into 24 time zones, each roughly 15 degrees of longitude apart.
- UTC (Coordinated Universal Time) is the primary time standard
- GMT (Greenwich Mean Time) is often used interchangeably with UTC
- Time zones east of UTC are ahead, west of UTC are behind
- Some regions observe Daylight Saving Time, shifting clocks by 1 hour