Weaving consists of interlacing two sets of yarns or threads to form a fabric. While the warp threads are held in place on a frame, weft threads are passed over and under the warp threads.[more]
Warp and weft threads can be interlaced in several ways, giving rise to different patterns. The fraction denotes a weave pattern obtained by repeatedly passing the weft thread over warp threads and then under threads.
Some classical weave patterns are a plain weave (1/1) and twill weaves (2/1, 2/2, 3/1).[less]
For more information, see http://en.wikipedia.org/wiki/Weaving.