Plain English Meaning
The Earth is split into 24 vertical strips, and within each strip everyone keeps the same clock time. Cross into the next strip and the time changes by one hour. Aviation uses one common clock — UTC — so pilots and controllers anywhere in the world are talking about the same moment.
Full Definition
Geographic regions of the Earth that share a common standard time. The world is divided into 24 time zones, each generally 15 degrees of longitude wide, with each zone differing from its neighbors by one hour. Time zones are referenced to Coordinated Universal Time (UTC), the standard used worldwide in aviation.
Context Anchor
Seen when planning flights across regions, reading weather times, checking airport operating hours, and converting local time to Coordinated Universal Time, often called UTC or Zulu time.
Derivation
The word zone comes from the Greek zone, meaning a belt or band wrapped around something. Time zones are literally bands wrapped around the globe, each holding its own time.