Unlike other light sources, LED's usually don’t suddenly “burn out.” Instead, they gradually fade in brightness after an extremely long time. LED useful life is generally based on the number of operating hours until the LED is emitting 70% of its initial light output. Good quality white LED's in well-designed fixtures are expected to have a rated useful life on the order of 30,000 to 50,000 hours; whereas a typical incandescent lamp lasts about 1,000 hours. The difference is staggering. By going with LED lights, you'll save money by using less bulbs. Plus, you'll be saving the Earth by creating far less waste.