Slip Stitch (sl st)

The slip stitch is a great way to tighten up the shape of your work and to finish off edges.  Unlike in knitting, there is no need to "bind off" your piece after you have finished crocheting it.  But, sometimes, you might want to create a border around a pot holder, for example, and really define its shape. 

The slip stitch involves inserting your hook into the stitch below (or, if you are working along the side of a crocheted piece, into the side of a stitch), yarn over, pull through a loop and keep going to pull that same loop through the loop on your hook.  You should now have just one loop on your hook and have completed a slip stitch.  It's like creating a row of chain stitches on top of the row you've just crocheted or along the side of a crocheted piece.