Yeah, it's hard to find anything on it. Looked all over internet as well and didn't get a good explanation either. Luxire can probably describe it better than I can but I'll give it a shot. It's a very, very sharp, defined crease that is sewn into the fabric with similar or same color thread. They iron in a crease first and then sew along that line. This is how perm creases were done before glueing the fabric like they do at JAB and MWH. It is possible to see the stitch but they sew it into the pattern to blend it. On mine, I can't see it unless i look at it from less than a foot or so and even then it's barely perceptible even in bright lighting. It is best if you have pleats since that's wehre the crease would start. It's very pronounced...even more so than the "glued" version on my other trousers. It may or may not be advisible on all materials and patterns. It worked on the pattern I chose and will be on my next order since there is similar pattern. I took a picture but it's impossible to see the stitches even close up. I'll post later tonight. You'll see what I mean.