A Unix timestamp (also called epoch time) is the number of seconds that have elapsed since January 1, 1970 00:00:00 UTC. It is widely used in programming to store and compare dates and times as a simple integer.

What is the difference between 12-hour and 24-hour time?

12-hour time uses AM (ante meridiem, before noon) and PM (post meridiem, after noon) with hours running 1–12. 24-hour time (also called military time) runs from 00:00 to 23:59, removing any ambiguity about morning vs. afternoon.

How do timezones work?

The world is divided into roughly 24 timezone offsets based on the UTC (Coordinated Universal Time) standard. Each timezone is offset by a number of hours (and sometimes half-hours) from UTC. For example, US Eastern Standard Time is UTC−5, meaning it is 5 hours behind UTC.

What is DST (Daylight Saving Time)?

Daylight Saving Time is the practice of moving clocks forward by 1 hour in spring and back in autumn to extend evening daylight. Not all countries observe DST. The timezone offsets shown on this page use standard (non-DST) offsets.