So we’ve reviewed casting on stitches (a number of ways) and increasing stitches (also a number of ways). Now let’s look at ways to decrease.
Basically, there are two methods: passing a stitch over, or knitting (or purling) two into one. Let’s look at the passing method first.
SKP (slip, knit, pass) aka skpsso (slip, knit, pass slip stitch over)
We slip one stitch, passing it from the left needle to the right as if to purl (this keeps it from getting twisted, thereby preserving the “knit” look).
Next, we knit one stitch.
Finally, we lift the slipped stitch with our left needle, bring it over the stitch just knitted, and drop it.
The resulting slipped/dropped stitch will lean toward the left. Keep this in mind when you’re choosing how to decrease.
k2tog (knit two together)
Just as it sounds, you insert your right needle, knitwise, into the front of the second stitch on your left needle and also the front of the first stitch.
Then you knit both of these stitches at the same time.
The resulting k2tog stitch will lean slightly toward the right. This makes an effective counterpoint to the left-leaning SKP. Consequently, many patterns that call for a decrease at both ends of a row will prescribe a SKP toward the beginning and a k2tog toward the end of the row.
But the k2tog can also be done by knitting into the back of two stitches. The results will be subtly but detectably different than the k2tog performed from the front.
The k2tog has a corollary, p2tog (purl two together). This is always performed from the front of the two stitches to be purled.
And if you’re really dexterous, you won’t be intimidated by p2tog’s relative, p2togb (purl two together back). Though some would rather train to be a contortionist, if you take your time and have not knitted too tightly, you can indeed go into the backs of two stitches at once and purl them together.
If the pattern needs to decrease by two stitches, it can either call for you to knit three together, or it can combine the SKP with the k2tog in this way:
Slip one stitch purlwise.
Knit the next two stitches together.
Pass the slipped stitch over the results.