Edison did not invent the light bulb

Inventors before Edison had made electric lights. Edison's team developed a long-lasting carbon filament bulb and a system to supply power, making electric lighting practical.

Context

Inventors in several countries built electric lamps before Edison. Humphry Davy demonstrated an electric arc light in the early 1800s, and in the 1840s and 1850s others experimented with glowing filaments in glass bulbs. Joseph Swan in England produced working carbon-filament lamps in the late 1870s and demonstrated them publicly in 1878 and 1879, at about the same time Edison was developing his own.

What Edison and his team did contribute was a practical, commercially workable system. They found a high-resistance filament that burned long enough to be useful, a better vacuum inside the bulb, and the generators, wiring, and sockets needed to supply power to homes. Their carbonized-bamboo filaments and the lighting of Pearl Street Station in New York in 1882 are usually cited as milestones in that process.

Patents and credit were fought over for years. Edison and Swan eventually merged their British interests into a joint company, Ediswan, in the 1880s. Historians therefore tend to describe the light bulb as the result of many contributors rather than the work of a single inventor, with Edison's role being to make electric lighting a widely usable product.