Increases
Increases are techniques used to add new stitches to make your knitting wider, commonly used for shaping sleeves, shoulders, and necklines.
Explanation
Increases are techniques used to increase the number of stitches on the needle, making the knitting wider. There are many ways to increase: M1R (make one right), M1L (make one left), KFB (knit front and back), and YO (yarn over). The choice of increase technique depends on whether you want the increases to be visible or invisible. Increases are typically used on sleeves (to make them wider going up the arm), on raglan shaping, and for shoulder shaping.