It is a very fine web-like fusible that is used between two layers of fabric to fuse them together, it doesn't add any thickness. It comes in strips that you csn use for hemming, or in sheets with a paper backing that you can draw a pattern on, for applique. Then you can fuse the applique to your background. It will add a little stiffness to the applique, but not a lot. Some times I just add a small piece between the applique and background to hold it in place.