Christmas lights, known in the United States as "holiday lights," usually constitute a decoration based on strings of electric lights, as a form of Christmas decorations. They can be used both indoors and outdoors, with many variations in color, type and size. Since ancient times, festive decorations have been used to celebrate special occasions. Christmas lights were first used in 1840 when Edward Johnson, an American inventor, first presented them to the public. Since then, many countries have adopted this tradition of using lights to celebrate Christmas. Christmas lights are a special part of the holiday season, associated with the traditions of taking walks outdoor after dark, looking and admiring the lights. In addition, shops and restaurants often use the lights in their storefronts or windows to add to the festive atmosphere. For these reasons, many families use one or two strands of lights on Christmas trees, and place colored lights around the house and yard. Some cities also host large displays of Christmas lights outside, usually for public viewing. These generally take the form of a series of trees, strings of lights, and various seasonal characters and symbols. In many cases, there will be a live performance of holiday music in accompaniment with the lights. Such displays have become a popular form of entertainment during the holiday season. All in all, Christmas lights are a beautiful and integral part of the holiday season, creating a festive atmosphere that is enjoyed by both adults and children alike.