What was started so that countries could have longer periods of daylight and use needed energy resources during WWI and WWII? (3 words)

Daylight Saving Time

Explanation:

Daylight Saving Time also known as Daylight time or Summer time is the period of the year when the clocks are set to one hour later. The aim is usually to decrease energy use and increase economic gains.

This practice was first proposed by George Hudson in 1895 but it was only in the 20th century that many countries started using it. Currently, 70n countries change their clocks during summer months, mostly in the Northern Hemisphere.