The 'Double Crochet' used to be to put your first double crochet in the 4th chain from the hook and chain 3 at the end of the row. Maybe some people still ch 3 for double crochet but I've heard that if you ch 2 at the end of a dc row then the sides would be straighter and I like the ch 2 for the double crochet but does that mean that the double crochet is the 3rd ch from the hook instead of from the 4th ch from the hook?

The single crochet is the 2nd ch from the hook and the half double crochet would be the 3rd ch from the hook cause it's a ch 2. So if the dc is the 3rd ch from the hook then the hdc and the dc would be putting the hook in the same ch(3rd ch) when starting and chaining 2 at the end of the row which would be alright. So, does anybody know what ch that the first dc is in - the 3rd or the 4th ch from the hook on the foundation chain?