/diy/ - Do It Yourself

>>1285952
If they have built-in resistors, you likely won't need an external one, but check the datasheet to find out what voltage they're meant to be run at, the resistor will provide the right amount of current only at or near that voltage.
You need current limiting because once the LED reaches the voltage it needs to actually turn on, it starts to draw current at a much higher rate as the voltage increases more, far more than it is safe for it to handle (see pic.)

>>1285953
Those will work if you're making your own boards, but I'd get a kit of through-hole resistors for prototyping, and because you'll need them for literally any other electronics project you want to do.