Thomas Edison was the inventor of the first commercially used light bulb. Though he was not the first; his version was much more practical compared to the ones invented at the time. His first demonstration of this incredible invention was in 1879 at Menlo Park, in the United States.
A light bulb consists of a glass outer shell and a type of filament that is connect to a conductor which transmits power/electricity back to the filament, this heats it to a point where it gives off light. This invention was not only an incredible innovation but was so cheap, at the time, that Thomas Edison said this " After my invention only the rich will burn candles." They were also more efficient than candles, and safer.
Today's light bulbs are incredibly complex compared to the original. Today we can use gas or very small hardware to create huge amounts of light these are called florescent or led lights.