E26

E26 is a common type of screw-in light bulb base, widely used in North America and many other parts of the world. It is also known as the medium screw base. The designation "E26" refers to the base's diameter in millimeters, which is 26 mm. This base is standardized by the International Electrotechnical Commission (IEC) as IEC 60061.

The E26 base is designed to be compatible with standard Edison screw-in sockets. Its threading allows for easy installation and removal of light bulbs. This standardization has made it a ubiquitous feature in residential, commercial, and industrial lighting fixtures for decades, accommodating a wide range of incandescent, halogen, CFL, and LED bulbs.

While E26 is the North American standard, a very similar base, the E27, is prevalent in Europe and many other regions. The E27 base has a diameter of 27 mm. Although visually similar, the 1 mm difference means that E26 and E27 bulbs are not directly interchangeable in all sockets, though adapters are sometimes available. The E26 base is typically associated with a voltage of 120V in North America, whereas the E27 base is commonly used with 220-240V.