Unlike HID bulbs, light-emitting diode (LED) bulbs do not operate with a filament. Instead, they transfer current through a semi-conductor. This emits photons, and boom – let there be light. LED headlights have also overcome halogen in popularity in recent years.
LED headlights need extra heat sinks and fans to stay cooler, which can add to the price tag and make it difficult to fit an LED headlight into a traditional halogen headlight housing during installation. But their cooler operating temperature makes them more eco-friendly and gives LED headlights the ability to run almost indefinitely.