On this day in 1918, Congress introduced Daylight Saving Time. The goal: to save fuel during World War I.

Does Mikey Like It? Actually, no one liked Daylight Saving Time much. The one-hour time shift was later repealed, but it was brought back in 1942.

What Is Daylight Saving Time, Anyway? A change in the standard time of each time zone. Time zones were first used by the railroads in 1883 to standardize their schedules.

An International Flavor. Before that, every major city and region set their clocks according to local astronomical conditions.

International Standard Time... called for adopting a standard ~ or mean ~ time with 1-hour variations between zones.

All On the Same Clock? The American law by which we turn our clock forward in the spring and back in the fall is the Uniform Time Act of 1966.

Do We Have To? The law does not require anyone to observe Daylight Saving Time. It merely says that, if we do observe Daylight Saving Time, everyone needs to do it the same way.