How to Crochet in the Round

Crocheting in the round is continuous in that you do not turn at the row, but go around and around until finished.

Crocheted Tube

A crochet tube can be used for phone or IPod sleeves, for example. To crochet in the round, you tie a slipknot and make a foundation chain as usual (the pattern will specify how many to chain). Instead of beginning in the second chain closest to the hook, you begin in the first chain right next to the slipknot. Slip stitch the ends together to form a ring: insert the hook into the loop of the first chain next to the slipknot, yarn over, and full the yarn through both loops on the hook. If you are counting rows, mark the start of the round (a stitch marker makes this handy). For single crochet, proceed by making a single crochet in each chain.
 

Crocheted Circle

Crocheting in the round generally refers to this method which creates a tight, flat circle. Crocheting a circle is handy for making amigurumi, or the Japanese art of crocheted stuffed animals. You begin in the same way as crocheting a tube, by joining the two ends of a foundation chain together with a slip stitch. The stitches in the first round are worked inside the ring to form a tight center. In other words, you insert the hook through the center of the ring, YO, and pull loop through the ring (should be two loops on the hook). YO again and pull loop through both strands. This is one single crochet into the center. The circle is then increased with each round, creating a spiral outward. You should mark the beginning of rounds with a stitch marker to keep track of your progress.
This video demonstrates a crocheted circle for amigurumi.