The art and science of constructing fabric by interlooping of yarn loops, through the use of needles and a “loop within a loop”. The most essential unit in a knit fabric is the loop or stitch. A vertical row of stitches is called a WALE; the horizontal or crosswise row of stitches is known as a COURSE. The number of wales per inch, measured across the fabric depends on the count or size of the yarn used, and the number of needles per inch in the machine. The two major classes of knitting are warp and weft.