If you forget, you will be an hour early for events tomorrow (Sunday). If you accidentally set your clocks ahead, you will be two hours early!
Safety officials suggest this is a good time to check the batteries in your smoke detectors and carbon monoxide detectors as well.
The main purpose of Daylight Saving Time (called "Summer Time" many places in the world) is to make better use of daylight. A poll done by the U.S. Department of Transportation indicated that Americans liked Daylight Saving Time because "there is more light in the evenings / can do more in the evenings."
Daylight Saving Time also saves energy. Studies done by the U.S. Department of Transportation show that Daylight Saving Time trims the entire country's electricity usage by a significant, but small amount, of less than one percent each day with Daylight Saving Time. We save energy in both the evening and the morning because we use less electricity for lighting and appliances.
Daylight Saving Time begins for most of the United States at 2am on the second Sunday of March. Time reverts to standard time at 2am on the first Sunday of November. In case you were wondering, these dates are the new dates for the changes, as of 2007 (they used to be in April and October).
For more information about Daylight Saving Time in the US and around the world, check out webexhibits.org/daylightsaving/index.html.