Designed to decorate homes and trees during the holiday season, Christmas lights (aka fairy lights) are very popular during the holiday season.
Common types of lights are incandescent light bulbs, LEDs, fiber optics or in times of old - candles! Christmas lights can be animated using interrupter bulbs or electronically. LEDs provide a nice modern touch to a christmas tree, and are very safe.
Some modern Christmas lights have covers over the bulbs and are themed: football, flowers, ducks, Guinness, cats etc. These lights are widely available on eBay.
Nowadays, Christmas lights are wired in parallel, which means that if one bulb goes the rest will still work.
ALWAYS follow the manufacturer's safety restrictions. If you have questions, consult the manufacturer or an electrician.
Suggested searches for lights on eBay:
Try this search for decorative lights
Try this search for collectable lights