Single crochet is one of the more common stitches you'll run across in crochet patterns, and is especially popular for use in amigurumi designs. Because of its short height, it creates a more dense fabric than other stitches. You begin by making a foundation chain, chaining exactly the number of stitches you wish to have in your sc row, then complete these steps:
*Insert hook in stitch, yarn over and pull up loop (Figure 1), yarn over and draw through both loops on hook (Figure 2); repeat from *.
You can also get a visual look at the single crochet stitch by watching this video; the sc technique is covered about 1 minute into the video: