hdc = half double crochet
The half double crochet comes halfway between a single crochet and a double crochet in height.
Make a foundation chain one chain more than the number of half double crochet stitches called for. Skip first 2 chain stitches (will count as the turning chain). Yarn over hook once, insert hook from front to back in the center of the third chain from the hook.
Yarn over, draw the yarn through the chain (3 loops on hook).
Yarn over, draw through 3 loops on hook (one half double crochet complete).
Yarn over, insert hook in the center of next chain, yarn over, draw yarn through stitch, yarn over, draw yarn through 3 loops on hook. Repeat across to end of foundation chain.
To begin the second row, turn your work. Chain two for the turning chain.
Skip the first half double crochet below the turning chain. Yarn over, insert hook from front to back under the top 2 loops of the next half double crochet in the row below, yarn over, draw yarn through stitch, yarn over, draw yarn through 3 loops on hook (first half double crochet complete). Repeat this step in each half double crochet across and in the top of the turning chain at the end of the row.