Daylight Savings is the practice of setting the clock forward by one hour during the warmer months to extend evening daylight. This typically occurs in the spring, when clocks are moved forward, and is reversed in the fall, when clocks are set back to standard time. The main goal is to make better use of daylight and conserve energy. The idea was first proposed by Benjamin Franklin in the 18th century, but it wasn't widely adopted until the 20th century. Many countries participate in Daylight Savings, although some regions, like parts of Arizona and Hawaii, do not observe it.