Purling is the act of forming a stitch that looks like the back side of a knit stitch.
Purling is the act of forming a stitch that looks like the back side of a knit stitch. Yarn is held in the front of the work and the right needle enters the stitch on the left needle from the backside. This forces the stockinette side of the stitch to the backside of the work and results in a purl bar forming on the front side of the fabric.
When you purl every row, you also get garter stitch. Above the dark needle is garter stitch done by purling every row. Below the dark needle is the traditional knitted garter stitch. The gap in which the dark needle is resting is a two row section of stockinette stitch that was created when the switch from the knit row to a purl row happened. As you can see, garter stitch is also forming above the dark needle when you purl every row!
