Hi Hootrocks,
single crochet is through 2 once, double crochet is through 2 twice, triple crochet is through 2 three times.

single crochet is chain 1 at end of row and go into the 2nd chain from hook when you start. To remember this - 2 comes after 1 when counting.(1, 2)

half double crochet is chain 2 at the end of row and go into the 3rd chain from hook - 3 comes after 2 when counting.(1, 2, 3)

double crochet is chain 3 at the end of the row and go into the 4th chain from the hook - 4 comes after 3 when counting.(1,2,3,4)

I'm just trying to simplify it.

So if you are doing a single, half double, double or triple crochet, you know that if you are chaining 1 at the end of the row then you need to skip one at the beginning of the row(sc) and if you are chaining 2 at the end of the row, you are skipping 2 at the beginning of the row(hdc) and if you are chaining 3 at the end of the row, you are skipping 3 at the beginning of the row.(dc) If you are chaining 4 at the end of the row, you are skipping 4 chains at the beginning of the row.(triple(tr) crochet).
The number of the chains at the beginning of a row is the height of the stitch.

Although some people chain 2 when doing a double crochet - I've done that too. I've done it both ways. Sometimes I chain 2 and sometimes I chain 3 when doing a dc but the books say to chain 3 for a dc and I want to do it right so when I do a dc I chain 3 even though a chain 2 makes a neater edge.