There are any number of cited reasons for the implementation of Daylight Saving Time.

Timeanddate.com does a good job of explaining its origins.

Daylight Saving Time is a seasonal time change measure where clocks are set ahead of standard time during part of the year, usually by 1 hour. As DST starts, the Sun rises and sets later, on the clock, than the day before.

Today, about 40% of countries worldwide use it to make better use of daylight and to conserve energy.

To read more click here.