Crochet work may be comprised of a number of different stitches. One common crochet stitch is the half double crochet, a stitch that is taller than a single crochet, but shorter than a double crochet. To make a half double crochet stitch, yarn over, insert the crochet hook into the appropriate stitch of the previous row, yarn over and pull the hook back through the stitch. Yarn over again and draw that loop through the three other loops on the hook to complete the stitch.
Half double crochet, abbreviated hdc, is a term typically used in U.S. crochet patterns. It is also known as half treble crochet, or htr, in the U.K. and other countries. International symbol patterns denote placement of a half double crochet stitch with a symbol that resembles a capital letter T.
The first step, to yarn over the hook, is as simple as it sounds. Take the yarn coming from the skein, which is also called the working yarn, and drape it over the hook from back to front. Each yarn over counts as one yarn loop on the crochet hook. After completing this step, the hook will have two loops.
Next, insert the hook into the desired stitch of the previous row. If the previous row is the foundation chain, place the hook through the middle of the chain stitch. On a piece with several worked rows, an oval shape will be visible across the top of the stitches in the last row. Put the hook under both sides of this oval unless the instructions say to work in the front loop or back loop only. The front loop is the side of the oval closest to you, and the back loop is the side of the oval farthest away.
With the hook inserted into the stitch, yarn over again. Draw the hook back out of the stitch to its starting position, making sure that the loop formed by the last yarn over remains on the hook. At the end of this step, there will be three loops on the crochet hook.
Yarn over a third time, after which the hook will have four yarn loops on it. Catch the final loop formed by the last yarn over in the hook and draw it through the other three loops. After this step, the half double crochet stitch is finished and there will once again be only one yarn loop on the crochet hook. Continue crocheting the project as specified by the pattern.