A batten is most commonly a strip of solid material, historically wood[1] but can also be of plastic, metal, or fiberglass.
The spacing of the battens on the trusses or rafters depend on the type of roofing material and are applied horizontally like purlins.
Rainscreen construction uses battens (furring) as part of a system which allows walls to dry out more quickly than normal.
Board-and-batten is also a synonym for single-wall construction, a method of building with vertical, structural boards, the seams sometimes covered with battens.
In the lighting industry, battens refer to linear fittings, commonly LED strips or using fluorescent tubes.