Ceiling fan bulbsThe small E12 or the standard E26 base, and the fan's wattage limit. → Recessed light bulbsBR30 or BR40 by can size, the label inside the can, retrofit kits and dimmers. → Bathroom vanity bulbsGlobe bulbs such as the G25, the base to check, and damp and wet ratings. → Bathroom heat lampsThe infrared bulb the heater's label names: 250 watt BR40 or R40 on Broan's bulb heaters. → Bathroom fan lightsThe bulb and most watts each fan's manual gives, from a 14 watt LED to a 100 watt bulb. → Outdoor light bulbsDamp or wet ratings for porch and outdoor lights, and bulbs on dusk-to-dawn or motion sensors. → Enclosed fixturesWhich LEDs can go under a closed glass dome, and what the box says. → LEDs on a dimmerA dimmable LED and an LED-rated dimmer, and how to fix flicker and buzz. → Bulbs keep burning outWhy bulbs fail early, in the makers' words: the fixture, heat, the dimmer, switching and shaking. → LED glowing when offWhy an LED can glow faintly with the switch off, from Leviton's support pages, and what to check. → General guidance from manufacturer and standards data. Products vary, so check the label and the maker's instructions.