A weaving term for yarns in woven fabrics and carpets which run lengthwise. Warp yarns are usually delivered to the loom from a beam, a large spool with hundreds of ends wound on it, mounted behind the loom. Woven carpets usually have three sets of warp yarns, which may be wound on three loom beams. These include stuffer warp for lengthwise strength and stiffness, pile warp which forms the carpet surface tufts, and chain warp which interfaces with fill yarn to lock the structure together.