The Edison screw fitting is a system of light bulb connectors, developed by Thomas Edison in 1909 under the Mazda trademark. The designation Exx refers to the diameter in millimeters, e.g. E12 has a diameter of 12 mm.
In the United States, the standard size for general purpose lamps is E26. Other base sizes are used for small lamps, such as E12 for candelabra fixtures and...
