Light Bulb History - From Incandescent and Halogen Lamp to LED
Every safe light source in the history had some sort of protection that protected source from the outer world and the outer world from the source. For electric light source, it was a bulb. Read more about light bulb history here.
Battle for incandescent light bulb lasted long and it was fought by many but in the end it was won and even today we can pick fruit of their victory. Read about history of incandescent light bulb.
At the first glance, halogen lamp does not look too differently than a standard incandescent lamp except it is smaller. But there is a difference. By a clever use of chemistry, it is made more durable, brighter and longer lasting. Read about history of halogen lamps and who invented halogen light bulb.
Accidental findings are sometimes equally important as deliberate ones. Such was the case with LEDS, light emitting diodes. They began as a side effect of usage of an electronic element to start a completely new branch of electronics. Read about history of light-emitting diodes.