Purl 2 together (p2tog) is a decrease that is often used on the wrong side of the fabric, or on the right side in a purl section (such as in the purl column of ribbing). It is just like purling normally, except you work in 2 stitches at the same time. Learn how to knit p2tog, what it looks like, and other similar stitches in this video and the accompanying tutorial at knitalongclub.com/p2tog/