What way round do v and 0v go on a LED?

On a standard LED, the longer lead (anode) is the positive side (v), while the shorter lead (cathode) is the negative side (0v). The cathode is usually marked with a flat edge on the LED casing. When connecting the LED in a circuit, ensure the anode is connected to the positive voltage and the cathode to ground or the negative side. This orientation allows the LED to light up when the circuit is powered.