Quick answer: wyif = with yarn in front (between you and the needles). wyib = with yarn in back (behind the needles, away from you). These tell you where to hold yarn when slipping a stitch.
What they mean
These abbreviations specify where the working yarn sits when you slip or work a stitch. Getting it wrong creates accidental yarn overs or twisted stitches.
When you see them
- Slip stitch patterns: sl1 wyif or sl1 wyib
- Brioche knitting
- Mosaic colorwork: slipped stitches always specify yarn position
- Selvedge instructions
How to do it
- For wyif: bring yarn through the gap between needle tips toward you (yarn in front of work). Slip the stitch.
- For wyib: move yarn through the gap between needle tips away from you (yarn behind work). Slip the stitch.
- After slipping, return yarn to the correct position for the next stitch.
Common mistakes
- Moving yarn over the needle instead of between the needles — creates an extra stitch
- Forgetting to return yarn to correct position after the slip
- Ignoring wyif/wyib entirely — fabric will look wrong even if stitch count is correct