Material
Sewing thread
Stitch seams, repair a pocket, or bind folded paper with a suitable thread.
Get to know it
Use sound thread that does not snap under a modest hand pull. Ordinary sewing thread suits fabric seams; a stronger doubled thread can suit a small notebook. Very thick cord can tear paper or refuse to pass through a needle.
A seam is an arrangement of stitches, not just a strong thread. Short backstitches and reinforced handle attachments can help spread force. Test a scrap of the actual fabric before sewing the final piece.