Type of Interfacings
Interfacing (or Interlining), like fabric, is made of various fibers and constructions. You should select an interfacing that is compatible with the weight, hand, or stretch of the garment fabric. The interfacing should not change the weight of the fabric or drastically affect the appearance of the garment. Do not select interfacing by feel as all properties may change when an interfacing in attached or laundered. There are a number of interfacings characterized by weight, finish, fiber blends, and textures. Select interfacing based on the following criteria: fiber content, weave, finish (press-on or sew-in), color, and wright.
An interfacing is used to:

Maintain shape and prevent stretching and wrinkling of the area to which it is applied such as necklines, lapped closures, yokes waistbands, and pockets
Provide support and crispness to collars, lapels, cuffs, pockets, tabs, and flaps
Define the shape of and provide support to body sections of tailored suits, dres...