Ladder stitch
A ladder stitch, or mattress stitch, is a stitch which can be used to invisibly close seams from the outside of the garment or item. It is primarily used to close seams on stuffed items, such as pillows, mattresses, down coats or stuffed toys, where, after the stuffing is added, there is no access to the back of the fabric. It can also be used to repair split seams on these items or garments, or to alter clothing.