well,Selvage denim (also called selvedge denim) is a type of denim which forms a clean natural edge that does not unravel. It is commonly presented in the unwashed or raw state. Typically, the selvage edges will be located along the outseam of the pants, making it visible when cuffs are worn. Although selvage denim is not completely synonymous with unwashed denim, the presence of selvage typically implies that the denim used is a higher quality.
The word "selvage" comes from the phrase "self-edge", the natural edge of a roll of fabric. In this case, denim made on old-style shuttle looms. These looms weave fabric with one continuous cross thread (the weft) that is passed back and forth all the way down the length of the bolt. As the weft loops back into the edge of the denim it creates this