How Do Time Zones Work?

Time zones are geographical bands that share the same standard time. Understanding how they work is essential in a hyper-connected world.

The Concept of the 24 Meridians

Because the Earth is a sphere that takes 24 hours to complete one rotation (360 degrees), the world is theoretically divided into 24 vertical bands, each measuring 15 degrees of longitude (360 / 24). Every time you move 15 degrees east, you add one hour. Towards the west, you subtract one hour.

The Political Reality of Time Zones

Although the map should consist of perfectly straight bands, governments alter time zones for political and economic reasons. For example:

• China: Geographically it should have 5 time zones, but the entire country uses a single unified time (UTC+8).
• Half-hour zones: Countries like India use UTC+5:30, adding half hours to align sunlight without creating drastic internal gaps.

The IANA Database

Modern systems and apps like the CronoNova World Clock use the IANA Time Zone Database. This database encodes zone rules and names regions under the "Continent/City" format (e.g., America/New_York).

Frequently Asked Questions (FAQ)