On October 21, 1879, Thomas Edison filed for a patent on his design for a practical incandescent light bulb. He and his team had been experimenting with various filaments and vacuum conditions to achieve a long-lasting, reliable lamp. The patent covered key features such as a high-resistance filament in a nearly air-free glass bulb. Shortly afterward, Edison demonstrated his lighting system in Menlo Park, New Jersey. His work made electric lighting more useful for homes and businesses. The patent and the surrounding system helped usher in the electrical age in the United States.
