What is daylight saving time?

CNN explain’s daylight-saving Time – CNN.com

In the past, daylight-saving time began in April and ended in October. However, an energy bill signed by President George W. Bush on August 8, 2005 extended daylight-saving time as part of a long-term solution to the nation’s energy problems. The new law extended daylight-saving time by four weeks – beginning three weeks earlier and ending one week later.