Answer:
The outsole and upper are glued together during assembly. However, in order to allow the shaft to later be stitched to the welt, the insole is first placed on the shoe and temporarily fastened to the lasts with nails. To give the shoe its final shape, the upper is then lasted and pulled tightly.
Modern shoes are most frequently made of leather, fabrics, synthetic materials, rubber, foam, and plastic. Each has a particular purpose in shoes. Each material can be used in a sneaker, depending on the design. One of the cornerstones of shoe design is the choice of material.