The chapter focuses on focus on understanding the structure of knitted materials and predicting their deformation behavior. The classification of knitting machines is described briefly to present the diversity of knitted structures and variety in their mechanics. Two huge groups of knitted fabric: weft and warp structures were analyzed separately. In weft knitting it is focusing on base structures namely plain, rib, and interlock. Each structure was described from both production and properties points. The main accent was made on structure modeling and deformation behavior. The effect of both tuck and float stitches on the structure and properties of weft-knitted fabric was analyzed. In warp knitting, attention is focused on yarn disposition in the structure, diversity of loop size and shapes as well as loop types (open or closed), and underlap length.