Exactly as the name implies, stitching is done on many paper craft projects with a needle and thread, much the same as you would on fabric. Some clever crafters even add embroidery, but you have to be mindful about making too many holes in the paper which will result in perforation.
Faux stitching is artificial stitching, often done with pen work, a piercing tool or cutting dies that include a “stitched” edge. It gives the effect of stitching without the thread or the time and effort that real stitching takes.
It’s possible to buy patterns that allow you to add intricate stitched designs to your projects. The patterns indicate the needle holes, which are generally pierced before the thread is added, and give the crafter instructions on the order of stitching.
Stitching is generally added for aesthetic purposes, but it also acts to secure embellishments or layers of paper together. Often it’s used in conjunction with adhesives to ensure a permanent addition.