Width increasing is the process of increasing the number of stitches in the width or circumference of a swatch. This is done by transferring one or more loops on adjacent needles one needle over to increase the width of the row in the swatch, then creating a new loop to fill the gap so created.
There are many ways to create a new loop for an increase. Three common methods are tuck increases, which fills the gap with at tuck in the same direction as the knitting; the twisted tuck increases which fills the gap with a tuck constructed in the direction opposite the knitting direction; and split increases which use a split operation to allow the machine to knit through the same loop twice.