Daylight Saving Time (DST) - also called summer time; it is a local time for some countries that take over the year to make better use of daylight. Clocks are usually adjusted forward one hour when passing on DST and adjusted backward when summer time ends. Exact time of clock adjustment depends on local time zone. In the case of the United States it occurs at 02:00 local time but e.g. in the European Union the one-hour shift occurs at 01:00 UTC.
The change to Daylight Saving Time adjusts time of people activity to time when the Sun is over the horizon. In consequences it allows to use less energy in lighting houses. The additional advantage is better safety on roads. On the other hand the time adjustment has mixed effects on health and adaptation of inner biological clocks can last for several days.
Time changes in 2017
Sunday, March 12, 02:00 AM
Sunday, November 05, 02:00 AM