Incandescent light bulb granted a Hungarian patent (No. 34541) for a tungsten filament lamp that lasted longer and gave brighter light than the carbon filament. Tungsten filament lamps were first marketed by the Hungarian company Tungsram in 1904. This type is often called Tungsram-bulbs in many European countries. Filling a bulb with an inert gas such as argon or nitrogen slows down the evaporation of the tungsten filament compared to operating it in a vacuum. This allows for greater temperatures and therefore greater efficacy with less reduction in filament life. In 1906, William D. Coolidge developed a method of making "ductile tungsten" from
Phase-out of incandescent light bulbs the results of interim assessment from October 2015 to October 2016. It has been reported that the ban would be complete by October 2016. While not a complete ban, the UJALA plan in India sought to replace 770 million incandescent light bulbs with LED bulbs by 2019. This was expected to reduce energy consumption by over 100 billion kWh annually and reduce annual electricity bills by . As of April 2017, 229 million LED bulbs had been distributed across the country. The states of Tamil Nadu , Kerala and Karnataka in India have banned the use of incandescent bulbs in