Ask the Chatbot Games & Quizzes History & Society Science & Tech Biographies Animals & Nature Geography & Travel Arts & Culture ProCon Money Videos
time zone
Introduction References & Edit History Related Topics
Images
World map showing standard time zones, with each zone shaded and labeled by its offset from Greenwich Mean Time. The International Date Line is marked with a bold, zigzagging line in the Pacific Ocean, and variations for half-hour and other non-standard offsets are indicated. Continents, major countries, and oceans are labeled for reference. Map centered on New York, showing major international flight paths to cities such as London, Rome, Delhi, Sydney, Tokyo, and Honolulu. Arrows indicate the direction of travel, with numbers around the edge representing time zones crossed. A scale at the bottom explains that crossing one time zone equates to approximately one day of jet lag, with days of jet lag increasing as more time zones are crossed.
Quick Facts
Britannica AI Icon
Adding us as a Preferred Source tells Google you trust our content, so our articles show up more often in your Google Search, Discover feed, and AI Overviews.
verifiedCite
While every effort has been made to follow citation style rules, there may be some discrepancies. Please refer to the appropriate style manual or other sources if you have any questions.
Select Citation Style
Feedback
Corrections? Updates? Omissions? Let us know if you have suggestions to improve this article (requires login).
Thank you for your feedback

Our editors will review what you’ve submitted and determine whether to revise the article.

External Websites
World map showing standard time zones, with each zone shaded and labeled by its offset from Greenwich Mean Time. The International Date Line is marked with a bold, zigzagging line in the Pacific Ocean, and variations for half-hour and other non-standard offsets are indicated. Continents, major countries, and oceans are labeled for reference.
World time zones A time zone map showing standard time zones and the International Date Line.

time zone

chronometry
Written and fact-checked by
Britannica Editors
Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree....
Britannica Editors
Last updated
•History

News •

Daylight saving time 2026: It's time to change your clocks this Sunday (Nov. 1) • Oct. 26, 2026, 11:42 AM ET (Live Science)
When does daylight savings time change fall back? Not this weekend. Try November • Oct. 16, 2026, 9:19 AM ET (Indianapolis Star)

time zone, a zone on the terrestrial globe that is approximately 15° longitude wide and extends from pole to pole and within which a uniform clock time is used. Time zones are the functional basis of standard time and were introduced in the late 19th century as railways connected places that had differing local times.

The Editors of Encyclopaedia BritannicaThis article was most recently revised and updated by Erik Gregersen.