Frequently asked questions (FAQ) index

Here are some frequently asked time and frequency questions grouped by category. If you have a question, look for an answer here.
We'll add new questions to this list as we receive them.

Precision	The current time, precision methods, Global Positioning System (GPS), and atomic clocks.
Leaps	Leap years and leap seconds.
History	General history, hours, minutes, & seconds, Daylight Saving Time (DST), and time zones.
Government	National and international timekeeping, Greenwich Mean Time (GMT), and time zone law.
Broadcast	Time signals broadcast by radio, telephone, and Internet.
Misc	Coordinated Universal Time (UTC), a.m./p.m., Modified Julian Date (MJD), and other related questions.