Goodyear Welt

In Goodyear-welt construction, a strip of leather (the welt) is stitched to the upper and insole, and the outsole is then stitched to that welt. The point is repairability: a cobbler can remove and replace the outsole multiple times without touching the upper, so a welted boot can last decades with resoles. It is heavier, stiffer at first, and more expensive to make than glued construction. For boots and dress shoes you intend to keep, it is the construction that makes a high cost-per-wear case real — provided you actually resole them instead of replacing.