The half double crochet (aka hdc) looks a bit more complicated than the single crochet but it’s not that tough. You can use it to get some variation in your Rnds or Rows of your piece and add a little bit of height too. I like to use them for hat brims because it adds a bit more yarn to the piece for warmth and looks nicer than just using the same stitch for the whole thing.

The slip knot is the first step to begin most crocheted projects. Think of it as kind of a mini noose; you can pull one end and it will tighten or close the loop, but when you pull the other end nothing happens. They’re very easy to make, here’s how:

Step 1: Start off by yo (yarning over)

Step 2: Insert your hook in the next stitch

Step 3: Yo and pull that loop through the stitch

Step 4: Yo again, and pull that loop through all three loops on the hook to finish up the stitch.

Remember how after turning a Row of scs you had to ch 1 and skip the ch to continue? Well, with hdcs you need to make 2 chs and skip them before continuing to keep it going evenly.
This also means that before measuring how many chs you’ll need before starting, you have to account for those 2 chs, so +2 to all beginning chs.