The ner tamid, Hebrew for eternal or perpetual light, is a lamp suspended above or beside the ark that holds the synagogue's Torah scrolls, kept lit at all times as a permanent fixture of the sanctuary. Traditionally an oil lamp, most ner tamid lamps in modern synagogues are electric, but the requirement of continuity, that the light never be allowed to go out, remains the defining feature regardless of the fuel or technology used to sustain it. Positioned prominently above the ark, the lamp draws the eye toward the Torah scrolls even when the ark's doors are closed, and it is often one of the few pieces of synagogue furnishing given individual artistic treatment, commissioned in worked metal or stained glass, or given as a dedicated memorial gift from a congregant or family.
Unlike the bimah or the ark itself, the ner tamid has no moment in the service when it is specifically used; it functions entirely through constant presence rather than participation in any particular ritual act, making it one of the few synagogue elements whose religious meaning is expressed purely architecturally rather than liturgically. Congregations sometimes site the ner tamid slightly differently within the same basic scheme, hanging it directly over the ark doors in some sanctuaries and just to one side in others, but in every case its placement keeps it visually associated with the Torah scrolls rather than with the bimah or the seating area, reinforcing that its light belongs to the ark's presence rather than to any part of the service that moves through the room.