A PN junction is a fundamental component, specifically in the operation of LED lights. It refers to the junction formed between a P-type semiconductor and an N-type semiconductor. In this junction, the P-type semiconductor contains an excess of positively charged holes, while the N-type semiconductor has an excess of negatively charged electrons. When a current passes through the PN junction, the electrons from the N-type region are pushed towards the P-type region, where they recombine with the holes. This recombination process releases energy in the form of light, resulting in the emission of photons.