Purl One Through the Back Loop
Purling through the back loop adds a little twist to a stitch. It is often used in twisted rib patterns or alongside cable stitches. You can also purl through the back loop to untwist mistakenly twisted stitches, but that looks a little different than the videos below.
Purling through the back loop is the purl equivalent of knitting through the back loop.
Abbreviations:
tbl - through the back loop
p1tbl - purl one through the back loop
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ENGLISH
CONTINENTAL