They are the three basic operations of a needle in knitting. In knit, the needle catches the yarn and forms a new, fully knitted loop. In tuck, the needle holds the yarn without releasing the old loop, creating a hidden bump that adds texture and width. In miss (float), the needle skips a course, so the yarn passes on the back, which thins the fabric and reduces stretch.
Combinations of these give structures such as pique, waffle or jacquard. Even if you do not see these words on a specification, they explain why textures differ in thickness, stretch and shrinkage.
knit stitchtuckmiss
