First, there was the Yule Log to light long winter nights. Then candles illuminated Christmas tree. Thomas Edison hung the first electric Christmas lights in his laboratory in 1880, which replaced the dangers of candle-lit trees with the dangers of electrical fires. Even the Great Depression couldn't stop people from buying Christmas lights.
The tradition of stringing electric lights may have started as a Christmas thing in America, but now it's a global phenomenon used for all kinds winter festivuses (festivi?). It's a practice we take for granted—come December, they're everywhere. The evolution of the Christmas light parallels that of the light bulb, with some remarkably ornate—OK, tacky—variations. But regardless of how they look, one thing's for certain: They're a much better option than sticking a candle in a tree.