Place stitches on stitch holder or waste yarn to keep stitches live to be joined, worked, or otherwise finished later on in the process. To do that, I will place stitches on stitch holder or waste yarn. I like to abbreviate waste yarn to WY.
In my patterns the standard instruction is: Place _________ stitches on stitch holder or WY.
Place Stitches on Stitch Holder
This means to slip (going into each stitch purl wise) the stitches onto a stitch holder pin or extra needle to safely hold those stitches until you are ready to work with them again.
Place Stitches on Waste Yarn (WY)
WY is threaded into a tapestry needle which is then passed through each stitch on needle purl wise . Loosely, but securely, tie WY ends together.
Place Stitches on Stitch Holder or Waste Yarn – a more in-depth explanation
A stitch holder is like a large pin and the open end is passed through each stitch in the same manner. If working from right to left, go into the stitches as to purl; if working from left to right, go into the stitches as to knit. WY can be threaded into a tapestry needle which is then passed through each stitch on needle in the same manner. Loosely tie WY ends together.
I prefer using WY to using a stitch holder. I can cut the yarn to a length so that my stitches can be laid flat if desired, it is flexible, and it doesn’t catch on anything. This is just my personal preference and you should use whichever method is most comfortable to you.
There are other times you may want to place stitches on waste yarn: If you need to check length, or circumference/width, threading the working piece onto a length of waste yarn will allow it to be laid flat, blocked, tried on. You may choose to do this if you need to “borrow” a needle from a project. If you are doing this, I suggest that you note which needles you are borrowing, including size and any distinguishing characteristics (maybe take a photo) so that when you want to resume that project you match the correct needles to the knitting.