People should change the time on their clocks on 2:00 A.M. on Sunday by moving it one hour forward. This applies to all states in the U.S. except Hawaii, Arizona, Puerto Rico and the U.S. Virgin Islands, who do not practice DST.
The adjusted time will be in effect until November 4, 2012.
As a review of history and the reason why we do daylight saving time. This comes from the time of WW1 when Benjamin Franklin supposedly suggested the idea to conserve energy because the work or office time gets adjusted to the period with the most sun. However, the practice did not become official until 1966, when the Uniform Time Act was ratified.
In other related news, several days after you adjust your clocks, on March 20, at 1:14 A.M. EDT the first day of spring and the vernal equinox, is set to take place.