The phrase "warp and woof" means a foundation or base upon which something is built, usually metaphorically. Literally, it means "fabric": warp and woof are the two components of a woven cloth.
The warp is the series of lengthwise strings of yarn through which the woof is woven. The warp is often thinner than is the woof but must be strong. Warp theads are kept taut throughout the weaving practice.
The woof is the yarn woven through, over and under the strands of the warp, to create the fabric. The woof does not generally have to be as strong as the warp, as it does not need to be stretched.
The woof is woven through the warp by means of shuttle, a piece of wood around which the woof is wound. This shuttle is passed between the strands of the warp, to create the fabric. Originally this was done by hand, but the Industrial Revolution introduced the mechanization of weaving.
The woof is alternately known as the weft. In America, it is also occasionally called the fill or filling yarn.
The word warp comes from the Old English verb "wefan", meaning "to weave". Warp, the threads which are thrown across, derives from the Old English "weorpan", "to throw".
- Photo Credit hand weaving loom image by green308 from Fotolia.com