I'm a little confused about this and can't find an answer that satisfies my curiosity... I've found a helpful thread (What does high attentuation actually mean in terms of types of sugar fermented?) but it doesn't really sort me out. Perhaps someone can help break it down for a noob... :)
I understand that your wort will contain a certain amount of fermentable sugars, and some unfermentable. I believe this to be around 60%-70% (depending on your grain choice, mash temperature, etc.).
Then we have yeast attenuation rates, which appear to be anything around 60%-85% depending on the strain, but this appears to be a mechanism for comparing different yeast types in a 100% fermentable sugar solution.
Does this mean that any particular yeast can only ferment, say, 75% of the fermentable sugars? So somewhere around 50% of the actual sugars in the wort will be converted to alcohol?
I'm sure this can't be the case and I must be missing something important here... what is the importance of understanding yeast attenuation?
I intend to buy BeerSmith at some point but I'm just at the beginning of the road at the moment so I'd like to get my head around the entire process as much as I can.