In knitting, TBL stands for "through the back loop". It is an abbreviation that is used in knitting patterns to indicate that the stitch should be worked through the back loop instead of the front loop. When knitting or purling through the back loop, the needle is inserted into the back of the stitch instead of the front, and the yarn is wrapped around the needle in the opposite direction. This creates a twisted stitch that can be used for decorative purposes or to add texture to a knitted piece. TBL is often used in combination with other knitting techniques, such as knit two together through the back loop (K2tog tbl), which is a knitting decrease that reduces two stitches to one.