I'm making a bit more than a gallon of yogurt here, starting with a gallon of skim milk and adding ingredients. I like my yogurt soft and just tangy enough, as we like to put it on cereal as well as make smoothies. Making yogurt is incredibly easy, but the results are generally outstanding. You can experiment and find the exact amount of tanginess you prefer and make the most delicious yogurts over and over specifically tailored to you and your family. You can have a lot of fun doing this and it's simply delicious.
Yogurt has been in use by humanity for more than 4,500 years. That is nearly as long as we've been brewing beer, and the two processes are not dissimilar.
In the case of beer, sugars that have been developed by breaking down carbohydrates in grains are naturally fermented by yeast; that is, they are eaten and digested into alcohol. If you were to develop this sugary mixture naturally (which happens all on its own in the correct conditions) you would undoubtedly eventually find naturally occurring yeasts that would appear to devour the feast and leave behind their lovely excrement (never thought of it like that did you?).
In our case, with yogurt, nearly the same process occurs naturally. Fresh milk whether from goat, cow, or dare I say rat, when left out, will most likely turn to yogurt through naturally occuring bacteria that develop in the milk over a course of hours. This was most likely the original yogurt discovery. Unlike the broken-down carbohydrates that our lovely friend yeast consumes, our little bacteria friends, mostly of the Lactobacillus variety, eat the sugars in milk a.k.a. Lactose and excrete Lactic Acid.
Your opinions may very, but I'm a big fan of both. I'd also argue that my worst batch of both homemade beer, and homemade yogurt, were still much better tasting than anything mass produced in either category.
So, lets start getting this thing going: