Christmas lights are decorative lights used during the Christmas holiday season, usually around or on Christmas trees, houses, and parks. Christmas lights come in a wide variety of colors, shapes and sizes, and can be used both indoors and outdoors. Christmas lights usually contain small strings of incandescent bulbs, although in recent years, LED lights have become increasingly popular for their energy efficiency and longer lifespan. When Christmas lights are used outside of a home or public space, it can bring a festive atmosphere to the area, creating a joyous and cheery atmosphere. Christmas lights often come in a variety of different decorations, such as illuminated deer, snowflakes, candy canes, bells, stars and other holiday related shapes. In some countries, such as the United Kingdom and Australia, it is traditional to keep Christmas lights up until the Twelfth Night after Christmas. Christmas lights serve as a reminder of the holiday season and are often used to bring cheer to a home during the winter months. During the Christmas season, many people like to decorate their homes with Christmas lights to add to the festive atmosphere. Christmas lights also have a fun and festive way of sprucing up a space, which is why they are often used to create outdoor winter displays.