Why are some bows measured in different inches?  Most are @ 28".  

Is it a bow at x#@28 is made to be pulled to 28 inches? A bow a x#@26 is made to be pulled to 26.  So on and so forth,

I'm new to trad gear.

Production bows are marked at 28(usually) because it is a common draw length. Customs can be marked at the draw length of the buyer. The bows aren't limited to the marked length in most cases, it just gives you an idea of what the weight will be at your draw.

Usually a bow maker will indicate what the draw range is for a particular bow.  For example, one bow company says that its 58" recurve is meant to have a drawlength in the range of 25-29".  If they don't indicate in their advertisements, you can probably call them and ask.  Personally, I wouldn't push the extreme end of the range, like a 29" draw for the 58" bow I mentioned.  But if you wanted a really short bow and had a 29" draw, you would at least know that the bow maker had tested the bow and found that it didn't begin to stack until somewhere after 29" (maybe it begins to stack at 29 1/4").

Just what's been said. I actually have two of my bows marked at 28.5" for the recurve and 27.5" for the longbow which is my draw length for each. It's a little inside joke actually as I am not that particular. I just asked the bowyer to build me the bows "somewhere in the 60-63# range" and just write down what weight it comes out at at my draw length. I think you have to pay $75 dollars to get your exact weight ordered with a Black Widow. How much to you have to pay to get it down to the HALF INCH!