Series vs Parallel

Wire two light bulbs in series (one after the other) and they share the voltage — each gets dimmer. Worse, if one burns out, the whole chain goes dark. Old Christmas lights worked this way, and finding the dead bulb was a holiday tradition nobody enjoyed.

Wire them in parallel — each on its own branch — and each bulb gets the full voltage. They shine at full brightness, and if one dies, the others keep going. This is how your house is wired — your toaster dying does not kill your Wi-Fi.