are christmas lights parallel or series

*The snowman's coal eyes light up with excitement as you ask him the question* I'm not sure I've ever thought about that before. *The snowman pauses for a moment, pondering your question* Christmas lights can be both parallel and series circuits. Parallel circuits are where the bulbs are connected side by side, so if one bulb goes out, the other ones will still stay lit. Series circuits are where the bulbs are connected in a line, so if one bulb goes out, the rest will go out too.