How are international time zones and DST rules decided?
Much like the United States, countries around the world choose their time zone borders legislatively. Many countries also observe some equivalent of DST, although the name is usually different, and the dates of the time changes may be different from U.S. rules. There is no single body that regulates time zones or daylight saving time around the world. Some countries provide little or no notice when they change their DST status and/or date rules. Seasons are opposite in the northern and southern hemispheres. So for countries in the southern hemisphere who observe some form of DST, the dates of the time changes occur at opposite times of year from the United States.
