Daylight Saving Time begins on the second Sunday of March, which is March 8 and ends on the first Sunday of November, that is November 1. So daylight saving time starts tomorrow, adjust your clock forward 1 hour at 2.00 AM on Sunday.

Here is an explanation from Wikipedia.

"Daylight saving time is the convention of advancing clocks so that afternoons have more daylight and mornings have less. Typically clocks are adjusted forward one hour near the start of spring and are adjusted backward in autumn. One of the many effects of this adjustment is that it shifts the start of the day closer to sunrise.

The practice is controversial.Adding daylight to afternoons benefits retailing, sports, and other activities that exploit sunlight after working hours,[3] but causes problems for farming, entertainment and other occupations tied to the sun. Traffic fatalities are reduced when there is extra afternoon daylight; its effect on health and crime is less clear."