Can someone explain to me the difference between leds connected in parralel and leds connected in a series and which one can u use only one resisitor

How to hook up LEDs

For the xbox, the best thing to do is wire in parallel. If you connect in parallel, you can have as many LEDs as you want. In series, you can only have between 3-5 before you ran into voltage problems. Usually, LEDs are connected in parallel.