For centuries, people used candles to light their homes in the dark days of winter. When they started putting up Christmas trees, they lit those with candles, too. Which led to a lot of fires.
That began to change once Thomas Edison created the first practical light bulb. Edison also was apparently the first to put electric lights outdoors at Christmas. The Library of Congress says he strung some together and hung them outside his Menlo Park, N.J., laboratory during the Christmas season of 1880.
Two years later, Edison's friend and partner Edward Johnson wired 80 red, white and blue light bulbs together and wound them around his Christmas tree. For added drama, he made the tree revolve.
In 1895, President Grover Cleveland ordered mutli-colored electric light bulbs for the White House family tree.
But electric Christmas lights were expensive and remained a rarity until 1903, when General Electric began to offer pre-assembled Christmas light kits. Their popularity grew after a novelty lighting company owned by Albert Sadacca and his brothers began selling strings of lights to the public. Their company cornered the Christmas light market until the 1960s.
Today China is the primary producer of Christmas lights, particularly the energy-saving LED variety, because of its plentiful cheap labor and large supplies of the necessary raw materials.