Christmas lights are a modern invention that dates back to the late 1800s. The earliest lights were small candles that were attached to the branches of the tree, providing a soft, warm glow. Over time, electrical lights were developed, and by the 1920s, they had become a popular Christmas decoration. Today, there are many different types of lights available, from traditional incandescent bulbs to modern LED lights that can create a variety of colors and effects. The use of lights on the tree has become an integral part of the Christmas season, bringing joy and beauty to homes across the world.