Start with a slip knot.  Next, crochet your chain. If you are working with a crochet pattern, then the pattern will tell you how long your foundation chain should be. If you are not working with a pattern, you will crochet a chain that is as long as you want for your project, plus add another two stitches. So for example, let’s say that you want to crochet a skinny scarf that is 10 double crochet stitches across. Make a foundation chain that is 10 + 2 (or 12). The reason that you add the extra chains is that those will count as the first double crochet, which you will see in a moment.  For now, though, you can just trust that this is the way that you do it, so yarn over and insert the hook into the third chain from the hook. So to recap, a double crochet stitch is:

Yarn over.Insert hook into the stitch where you want to place the dc stitch.Yarn over again.Pull through.Yarn over again.Pull through the first two of three loops on hook.Yarn over again.Pull through the remaining two loops on hook.

That’s all there is to it. Once you’ve completed the first double crochet stitch, you should see that it is standing to the right of what now appears to be another double crochet stitch; that’s the stitch that was created when you skipped the first three chains because they serve as the first double crochet stitch of the first row. Note: Where the instructions say “to the right” in this article is intended for right-handed crocheters. It will be the opposite for left-handed crocheters. Take a look at what double crochet looks like when worked in different loops. When you increase double crochet, you simply crochet two double crochet stitches into one stitch from the row below it.  When you decrease double crochet, you essentially have to make two consecutive stitches into one stitch. This is how you do that with double crochet:

Begin the double crochet stitch as normal. You will go through all of the steps until there are only two loops left on the hook (just before you do the final yarn over.)Leave the work on the hook just like it is. Yarn over, insert the hook into the next stitch. Work as you normally would by doing yarn over, pull through, yarn over, pull through first two loops on hook, and yarn over one more time.There should be three loops on the hook. Yarn over and pull the yarn through all three loops. This secures the two side-by-side double crochet stitches with a common stitch at the top, effectively turning them into one double crochet stitch to work into in the next row.

Here are the instructions for a front post double crochet stitch:

Yarn over.Insert your hook front-to-back through your work so that the post you want to crochet around a situation in “front” of your hook.Yarn over again and pull through. There will be three loops on your hook. You’re going to proceed with normal double crochet instructions at this point.Yarn over and pull through the first two of the three loops on the hook.Yarn over and pull through the remaining two loops on the hook.

A back post double crochet would be worked the same way except that you would insert the hook from the back of the work into the front of the work around the post where you want to make the stitch. The following techniques rely on the double crochet stitch:

The classic crochet granny square: Each cluster in a granny square is made up of three double crochet stitches. The only other things you need to know for this are how to crochet chains and work in the round.  Other granny crochet shapes: The double crochet is used to make granny circles, granny triangles and granny rectangles as well. Filet crochet: This terrific niche of crochet allows you to make letters and other great graphics in patterns that can range from early vintage designs to the most contemporary patterns. It is made using double crochet stitches and chain spaces. V-stitch: The v-stitch is another crochet pattern that uses a combination of double crochet stitches and crochet chains. The placement of the stitches and chains creates “V” shapes. This is a really popular 21st-century pattern option. Crossed double crochet: Whereas the v-stitch makes a pattern that looks like a v, the crossed double crochet (xdc) looks like x’s. It’s a great simple way to create a crochet fabric that looks more difficult than it really is to execute. Cluster stitch: Clusters, bobbles, and popcorn stitches can be worked using different basic stitches but it is very common to use the double crochet stitch.  Crochet shell stitch: Likewise, the shell stitch can be made in different heights but the double crochet shell stitch is most common. V-stitch crochet shell: This combines the dc v-stitch with the dc shell stitch. Simple mandala: Crochet mandalas can be made using many, many different types of stitches. However a simple favorite—the standard 12 round crochet mandala—relies entirely on double crochet stitches.