Guides & glossary

Understand time, zones & dates

Clear explainers on how the world tells time — the standards behind clocks and calendars, and how to work across them without confusion.

Time zones

UTC is the global time standard every clock and time zone is measured against. Here is what it is, why it exists, and how it differs from GMT.

GMT and UTC point to the same clock time, but they are not the same thing. One is a time zone, the other a global standard.

Why clocks spring forward and fall back, who observes daylight saving time, and how it affects scheduling across regions.

From the 24 lines of longitude to the messy political borders of real time zones — a plain-English guide to how the world tells time.

A practical checklist for finding a fair meeting time across countries — and avoiding the daylight-saving traps that derail recurring calls.

Why YYYY-MM-DD is the one date format that never causes confusion, and how to read full ISO 8601 timestamps.

Why February sometimes has 29 days, the exact rule for which years are leap years, and the astronomy behind it.