What is the difference between a time zone and a UTC offset?
An IANA time zone such as America/New_York contains clock-change rules that depend on the date. A fixed offset such as UTC−05:00 always remains five hours behind UTC.
Why can a local time be missing or occur twice?
Daylight saving changes can skip a range of local clock readings in spring or repeat them in autumn. The converter reports a missing time or asks you to choose the intended occurrence.
Can I use abbreviations such as CST or IST?
Abbreviations can refer to several different time zones. Search for a city or a full IANA identifier to select an unambiguous rule set.