Half double crochet, Double crochet, etc.

This is the fourth post in this series.  Please start here:
What do you need

Half Double Crochet (hdc)

This will be your first variation on a single crochet.  And it only has one difference.  The difference is that you're going to Yarn Over (yo) before you start.  No, really, that's all.

1. So be all prepared to make a single crochet.  Before you do anything else, wrap the yarn over your hook AS IF you were going to pull it through... but don't pull.  There are now 2 loops on your hook (yeah, it's kind of a stretch to call that one a loop, since it's just sitting there - but that's what it's called).
2.  Now, ignore that extra loop.  Use your tension finger to hold the loose yarn toward the rear of the piece, which will keep that loop on the shank of your crochet hook (or hold it with a finger on your hooking-hand if you must).  Now stick the hook into the work the same way you would for a single crochet.  Grab new loose yarn and pull it out of the stitch, just like in a single crochet.  But now, instead of 2 loops on the hook, you've got 3: the new one, the yarn over, and the original one.
3.  Now hook some loose yarn and pull through all 3 loops.

 Done!

Here's a video of it:
Half double crochet

Remember that a half double crochet requries TWO chains on the turn.

Double Crochet (dc)
There's only one difference between this and the half, and that's how many loops you pull through.  In fact, the way this works is the same as all remaining stitches - it never pulls through more than 2 loops at a time.  Once you master this, you're basically done.  Ready?

1. Yarn over, just like in the hdc.
2. Stick the hook into the next stitch
3. Hook some loose yarn and pull it out of the stitch - you now have 3 loops
4. Hook some loose yarn and pull it through TWO of those loops - the loop you pulled plus the original make 2 loops still on your hook
5. Hook some loose yarn and pull it through those two loops.  You're done.

Here's a video - she starts this one into a chain:
Double crochet

The double crochet needs THREE chains on the turn.

Triple Crochet (tc)
This is the same as the double, except that you wrap two loops around your hook before starting.  Then you still never pull through more than 2 loops, so you'll need to do that an extra time in order to finish.

Triple crochet needs 4 turning chains.

Now what?  Patterns and pattern reading
That's it, you've learned all of the stitches.  No, really.  The pretty things you see are just based on how those stitches are combined and what stitches you go into.  For that you'll need one more stitch
Skip (sk)
Okay, it's not a stitch.  But you'll need to know it.

If you've been working on the same sampler all this time, and you haven't made any major mistakes, you should still have 11 stitches - the turning chain plus 10.    If you need to, start a new piece.  Chain 11 and then single crochet back down (starting in the 2nd chain from the hook) it so you've got a good base to work with.

1. Chain 3.  This will pretend to be a double crochet. 
2. Now chain 1 more - this is just a chain.  ;-)
3. Skip the next stitch that you would normally go into.  Instead, double crochet in the next one.
4. Repeat steps 2 and 3 until you get to the end.  You should now have 6 posts with 5 empty spaces.  One of those posts was your chain, but it should look just like the double crochets now. 

Here are the same instructions again - the numbering is going to change a little, but the stitches are identical:

1. ch 3 (counts as dc)
2. *ch, sk 1, dc* repeat from * to * to end.  (6 dc)

Okay, let's stitch our way back across.

1. ch 3 (counts as dc)
2. *ch 1, dc in dc* repeat to end, finishing in 3rd ch of turning ch 4.
   

This looks a little different on paper, but looks the same in your work.  You do the chain 3 as your turning stitch to replicate a double crochet.  Then you chain 1.  Double crochet in the top of your prior row double crochet (which means skipping over the chain, but the instructions don't say so).  Keep doing that until the end, but now you skip the 1 chain you've always skipped, and use to top of the original chain3 as if it were the double crochet it's pretending to be.

You still have the same number of stitches.  To prove it, chain 3 and double crochet across.  Go into the same part of the stitch, whether it's a chain or a double crochet, until you get to the end.  At the end, you'll need to work into TWO chain stitches - the chain 1 and the pretend double crochet.

Then chain 3 and work another row of double crochet back again.  When you're done, you should still have 11 posts.

Let's do something fancier.

1. ch 4 (counts as dc and ch)
2. sk dc, dc in next dc
3. sk 2 dc, 5dc in next dc
4. sk 2 dc, dc in dc
5. ch, sk dc, dc in top of chain 3

Let's break that down

1. Chain 4 (that's our turning chain for a double crochet, plus another chain)
2. skip the next stitch (which is a dc) and double crochet in the one after (it's also a dc)
3. skip 2 stitches (dc's) and do FIVE double crochets all in the same stitch - this is the center of the piece, if that helps you find it.
4. skip two more stiches, then double crochet
5. chain 1, skip a stitch, then double crochet in the top of the next stitch, which is the chain 3 turning stitch that was pretending to be a double crochet

Look at that!  Kind of pretty, isn't it?  Now let's go back and count how many stitches we did:

1. ch 4 (counts as dc and ch)       - This is 2: a dc and a ch
2. sk dc, dc in next dc                 - This is 1: just the dc (skipping things isn't stitching it's just direction)
   
3. sk 2 dc, 5dc in next dc            - This is 5: the dc's
   
4. sk 2 dc, dc in dc                     - This is 1: just the dc
   
5. ch, sk dc, dc in top of chain 3 - This is 2: the ch and the dc
   

Now you can see clearly how we worked in toward the center, and mirrored our work back out again.  And we still have the same 11 stitches we've been working with the whole time.


How big is this thing gonna get?!?
The way you determine how many stitches make an inch is to crochet a sample piece with the yarn, hook, and primary stitch you're planning to use. If you make a piece that's about 20 stitches across and about 10 rows of double crochet or 20 rows of single crochet you should have a pretty good sample of how big your stitches are going to be. Then just use a ruler and figure out exactly how many stitches and rows you made per inch.

This is called "checking your gauge" and most patterns will tell you exactly how many stitches of what type to use for your sample, and what the measurements should be. If the final size of the piece matters (like for the slippers I'm making) you should *always* do this before starting the "real" piece. So for my slippers, I obviously have to end up with the right size *and* I can't change the number of stitches or I won't be following the pattern and it will all go wrong. So if my gauge is wrong, I change to a larger or smaller hook and make another sample to see if I've got it right. For something where size doesn't need to be as precise (like an afghan) you can just pick something comfortable and go with it.