Learn
Everything About Time Zones
Articles covering the basics, clock changes, scheduling across time zones, and the technical details behind how computers handle time.
What Is a Time Zone?
A clear explanation of what time zones are, why they exist, and how the world's 38 zones work in practice.
The BasicsWhat Is UTC?
UTC — Coordinated Universal Time — is the world's primary time standard. Here's what it is, how it works, and why software uses it everywhere.
The BasicsWhat Is GMT?
GMT — Greenwich Mean Time — is the historical predecessor to UTC. Learn what it means, where it's used, and how it differs from UTC today.
The BasicsWhat Is an IANA Time Zone?
IANA time zone names like 'America/New_York' are the global standard for identifying time zones in software. Here's why they exist and how to read them.
The BasicsWhat Does UTC Offset Mean?
UTC offsets like UTC+5:30 or UTC−8 tell you how far ahead or behind a location is from the world's time standard. Here's how to read and use them.
The BasicsWhat Is the International Date Line?
The International Date Line is where one calendar day ends and another begins. Here's where it is, why it zig-zags, and what happens when you cross it.
The BasicsHow Many Time Zones Are There?
The answer is more complex than you'd think — Earth has 38 distinct UTC offsets in use, not 24. Here's the full breakdown.
The BasicsWhat Is a Half-Hour Time Zone?
Countries like India and Iran use UTC offsets ending in :30. Here's why half-hour (and even quarter-hour) time zones exist and which countries use them.
Ready to use the tools?
Jump straight into any of our free time zone tools — no sign-up needed.
