Daylight Saving Time is a way of making better use of the daylight in the evenings by setting the clocks forward one hour during the longer days of summer, and back again in the fall. To remember which way the clock goes, keep in mind one of these sayings: "spring forward, fall back" or "spring ahead, fall behind." Learn more here about the rationale behind DST and its history, the effects on health, common expressions, where it is observed, and the ongoing debate around DST.