NEW YORK - Daylight Saving Time (DST) begins the second Sunday in March and runs until the last Sunday in October.

In the United States, DST was first introduced in 1918. But it wasn't until 1966 that the Uniform Time Act was established.

The law grants states the ability to opt out of DST, but nothing in the federal law allows them to exempt themselves from standard time.

Arizona and Hawaii don't use DST. And in Florida, lawmakers have just approved a bill, called the Sunshine Protection Act, to keep it going throughout the year in their state. The Florida bill still has to be signed by Gov. Rick Scott, and approved by Congress.

Most countries outside Europe and North America don't take part in DST.

One reason Congress used in enacting DST is that it saves energy. But, according to CNN, a 2008 U.S. Department of Energy study reported that daylight saving time reduces annual energy use by only about 0.03%. And a study that same year from the University of California-Santa Barbara found it might even increase energy consumption.