The purl stitch is one of the basic stitches to learn when loom knitting. The combination of the knit stitch and purl stitch can yield a plethora of beautiful designs. If you are barely learning to loom knit, I highly recommend getting acquainted with the Purl Stitch.
The purl stitch creates the small noose/bump like stitches on your knitted fabric.
Note: I already had a Purl stitch video, created back in 2011, technology has advanced just a tad and videos are a little clearer now, thus an update.