This left leaning decrease is easy to do, and the finished stitch is neater than some other options.
There are several common options for a left leaning decrease. Patterns may also tell you to knit two stitches together through their back loops (k2togtbl) or to slip one stitch, knit the next one, and then pass the slipped stitch over the knitted one and (skp). However, we think slip, slip knit (ssk) is the neatest and easiest way to do it, so unless the pattern says otherwise we use this one every time!
1 Slip the next two stitches knitwise, one at a time, from the left hand needle to the right hand needle. This twists them to tighten them up.
2 Insert your left hand needle through both front loops of the stitches you’ve just slipped, from back to front.
3 Wrap the yarn around anti-clockwise and pull the loop to the front, and off the left needle. You’ve decreased one stitch.