Timezones can be tricky in application development. Understanding the difference between UTC, GMT, IANA timezone names, and Daylight Saving Time (DST) is essential for avoiding time-shifting bugs.
UTC vs GMT
UTC (Coordinated Universal Time) is the global primary time standard by which world clocks are regulated. GMT (Greenwich Mean Time) is a timezone representing the local time in Greenwich, London. While they share the same offset (+00:00), UTC is a technical standard rather than a physical location timezone.
IANA Timezone Identifiers
Always store and configure timezones using IANA database identifiers such as America/New_York, Europe/London, or Asia/Tokyo rather than fixed offsets (like EST/EDT) because IANA identifiers account for Daylight Saving Time transitions automatically.