Slip Stitch is the shortest of all the crochet stitches and its main uses are for joining rounds, making seams, and carrying the hook and yarn from one place to another.
Insert the hook from front to back into the required stitch. Wrap the yarn over (yo) the hook and draw it through both the work and the loop on the hook. One loop remains on the hook and one slip stitch has been worked.
Hint: Take care not to work slip stitches too tightly as you can pucker your crocheted fabric.