Knowing what resistor to use is way to confusing for me. I thought I had figured it out. But then I started taking junk apart and trying to figure things out. I have run into a confusing issue. Almost every white 5mm LED I have used/seen requires 3.6ish V to 4.0 V max, but I have seen them with 5V going to it with just a resistor on it. Why isn't that LED burning out? Or is it the max current that matters?