In knitting

Knitting

Knitting is a method by which thread or yarn may be turned into cloth or other fine crafts. Knitted fabric consists of consecutive rows of loops, called stitches. As each row progresses, a new loop is pulled through an existing loop. The active stitches are held on a needle until another loop can...

, an increase is the creation of one or more new stitches, which may be done by various methods with distinctive looks.

Methods of Single Increasing (knitting)

• Yarn-over increase or "eyelet increase" -- The simplest increase is to do a yarn-over
  Yarn over
  In knitting, a yarn over is technique in which the yarn is passed over the right-hand knitting needle. In general, the new loop is knitted on the next row, either by itself or together with an adjacent stitch . The yarn-over may also be dropped on the next row, producing a longer stretch of yarn...
  
   between two existing stitches. On subsequent rows, the yarn-over will be knitted, making a new stitch. This disadvantage of this method is that a small hole (eyelet) is produced at the yarn-over. This can be improved by twisting the yarn-over stitch
  Plaited stitch (knitting)
  In knitting, a plaited stitch is a single knitted stitch that is twisted clockwise or counterclockwise , usually by one half-turn but sometimes by a full turn or more.-Methods:...
  
   - similar to a "make one" (below).

• Raised Increase -- Lift the strand connecting two knitted stitches in the row below onto the left needle (effectively producing a yarn-over
  Yarn over
  In knitting, a yarn over is technique in which the yarn is passed over the right-hand knitting needle. In general, the new loop is knitted on the next row, either by itself or together with an adjacent stitch . The yarn-over may also be dropped on the next row, producing a longer stretch of yarn...
  
  ) and knit it, either normally or twisted
  Plaited stitch (knitting)
  In knitting, a plaited stitch is a single knitted stitch that is twisted clockwise or counterclockwise , usually by one half-turn but sometimes by a full turn or more.-Methods:...
  
  . This method (especially if twisted) leaves almost no hole, since forming the yarn-over stitch from the (presumably tight) connecting strand draws the two neighboring stitches together.

• Bar increase -- Knit the stitch normally but without transferring the knitted stitch to the right needle; the same stitch is then knitted through the back loop. (Knitting through the front loop again is not feasible, since it would undo the first stitch.) This increase makes a bar or a nub on the fabric.

• Moss increase -- Knit the stitch normally but without transferring the knitted stitch to the right needle; the same stitch is then purled. This increase makes a bar or nub on the fabric.

• Lifted Increase -- For a right-side increase, knit into the right leg of the stitch of the row below the next stitch to be knit, then knit the next stitch. For a left-side increase, knit one stitch, then knit into the left leg of the stitch of the row below it. This kind of increase can be visually subtle.

• "Make One" (M1) -- Place a half-hitch loop on the needle between two stitches, either before or after, and twisted either left or right, depending on desired effect.

• Column of Increases -- A second strand of yarn or roving is passed up the piece. The second strand is used to make an extra stitch in each row by knitting a doubled stitch up from the lower row. The resulting piece has one more stitch in each row and each row is in the shape of an inverted V. The column of increases is used to make square sweater yokes.

Finally, a large number of increases in a row is best done by casting on

Casting on (knitting)

In knitting, casting on is a family of techniques for adding new stitches that do not depend on earlier stitches, i.e., stitches having an independent lower edge. In principle, casting on is the opposite of binding off, but the techniques involved are generally unrelated.Casting on can also be...

; examples include buttonholes, etc.

Role in fabric shaping

The typical use for increases and decreases

Decrease (knitting)

A decrease in knitting is a reduction in the number of stitches, usually accomplished by suspending the stitch to be decreased from another existing stitch or by knitting it together with another stitch.-Methods of Single Decreasing :...

 is to taper a flat piece of knitted fabric, e.g., in widening the sleeve

Sleeve

Sleeve is that part of a garment which covers the arm, or through which the arm passes or slips. The pattern of the sleeve is one of the characteristics of fashion in dress, varying in every country and period...

 of a sweater from the wrist to the biceps. However, increases and decreases can also be used to produce curvature

Curvature

In mathematics, curvature refers to any of a number of loosely related concepts in different areas of geometry. Intuitively, curvature is the amount by which a geometric object deviates from being flat, or straight in the case of a line, but this is defined in different ways depending on the context...

, i.e., to make the knitted fabric cup (positive curvature) or gather (negative curvature); in woven fabrics

Woven

A woven is a cloth formed by weaving. It only stretches in the bias directions , unless the threads are elastic. Woven cloth usually frays at the edges, unless measures are taken to counter this, such as the use of pinking shears or hemming.Woven fabrics are worked on a loom and made of many...

, this curvature is produced with darts, flares and gussets. A great advantage of knitted fabrics is that they can be shaped nearly invisibly without seams or cutting (as woven fabrics must) with increases, decreases

Decrease (knitting)

A decrease in knitting is a reduction in the number of stitches, usually accomplished by suspending the stitch to be decreased from another existing stitch or by knitting it together with another stitch.-Methods of Single Decreasing :...

, and/or short rows

Short row (knitting)

In knitting, a short row is a row that is not fully knitted; the work is turned before reaching the end of the row. Just before the work is turned, the yarn is generally passed around the next unknitted stitch to prevent a hole from forming at the turning point.The typical bobble provides a simple...

.