Slip stitch is and unworked stitch that has been moved from the left hand needle to the right hand needle. You can slip stitches knitwise and purlwise. Knitwise slip will bring the back loop forward and the front loop backward. To slip knitwise insert the needle as if to knit and move it to the right hand needle. Purlwise stitch doesn't alter the stitch in any way. To slip purlwise insert the needle as if to purl and move it to the right hand needle.