Editing Incandescent light bulb (section)

===Lamp bases===
{{Main|Lightbulb socket}}
[[File:Gloedelampe fatninger.jpg|right|thumb|40-watt light bulbs with standard E10, E14 and E27 Edison screw base]]
[[File:BCincandescentlamp.jpg|upright|thumb|The double-contact bayonet cap on an incandescent bulb]]

Large lamps may have a [[Edison screw|screw base]] or a [[Bayonet mount|bayonet base]], with one or more contacts on the base. The shell may serve as an electrical contact or only as a mechanical support. Bayonet base lamps are frequently used in [[Automotive lamp types|automotive lamps]] to resist loosening by vibration. Some tubular lamps have an electrical contact at either end. Miniature lamps may have a [[wedge base]] and wire contacts, and some automotive and special purpose lamps have screw terminals for connection to wires. Very small lamps may have the filament support wires extended through the base of the lamp for connections. A [[bipin]] base is often used for halogen or reflector lamps.<ref>{{cite web |title=Single-Ended Halogen Bases |url=http://www.bulbster.com/lightbulbs/singleended-halogen-c-783_43230.html |publisher=Bulbster.com |access-date=17 June 2013 |url-status=live |archive-url=https://web.archive.org/web/20130919152653/http://bulbster.com/lightbulbs/singleended-halogen-c-783_43230.html |archive-date=19 September 2013}}</ref>

In the late 19th century, manufacturers introduced a multitude of incompatible lamp bases. [[General Electric]]'s "[[Mazda (light bulb)|Mazda]]" standard base sizes were soon adopted across the US.

Lamp bases may be secured to the bulb with a cement, or by mechanical crimping to indentations molded into the glass bulb.

Lamps intended for use in optical systems have bases with alignment features so that the filament is positioned accurately within the optical system. A screw-base lamp may have a random orientation of the filament when the lamp is installed in the socket.

Contacts in the [[lightbulb socket]] allow the electric current to pass through the base to the filament. The socket provides electrical connections and mechanical support, and allows changing the lamp when it burns out.