Every now and then a pattern will require you to decrease on the purl side of the work. Just like right-side decreases, some purl-side ones lean right and some lean left. This tutorial shows you both: the purl 2 together (p2tog) decrease leans left on the purl side and right on the knit side, mimicking a right-side knit 2 together (k2tog). The purl 2 together through the back loop (p2tog tbl) and slip slip purl (ssp) both lean right on the purl side and left on the knit side and correlate with a right-side slip slip knit (ssk). (Note that p2tog tbl and ssp are about the same, except that a p2tog tbl twists the stitches and an ssp does not.)

Here’s a little cheat sheet to help you sort it all out…

P2TOG

Purl side: Leans left

Knit side: Leans right

Mimics: K2tog

P2TOG TBL + SSP

Purl side: Leans right

Knit side: Leans left

Mimics: Ssk