Lightbulb is the most useful invention

 

If there's a common theme to this list, it's that no major invention came from a single stroke of genius from a single inventor. Every invention is built by incrementally improving earlier designs, and the person usually associated with an invention is the first person to make it commercially viable. Such is the case with the light bulb. We immediately think of Thomas Edison as the electric light bulb's inventor, but dozens of people were working on similar ideas in the 1870s, when Edison developed his incandescent bulb. Joseph Swan did similar work in Britain at the time, and eventually the two merged their ideas into a single company, Ediswan.

The bulb itself works by transmitting electricity through a wire with high resistance known as a filament. The waste energy created by the resistance is expelled as heat and light. The glass bulb encases the filament in a vacuum or in inert gas, preventing combustion.

You might think the light bulb changed the world by allowing people to work at night or in dark places (it did, to some extent), but we already had relatively cheap and efficient gas lamps and other light sources at the time. It was actually the infrastructure that was built to provide electricity to every home and business that changed the world. Today, our world is filled with powered devices than we can plug in pretty much anywhere. We have the light bulb to thank for it.