What is an autolyse?
This is the fancy term for “mix only your flour and water together, and let it sit for twenty minutes before adding salt and yeast, and kneading”. No, I’m not being glib; it’s really that simple.
This means that enzymes in flour (amylase and protease, if you really want to know) begin to break down the starch and protein in the flour. The starch gets converted to sugar, and the protein gets reformed as gluten.
Why would you want to do this? When you knead the dough, aren’t you just trying to do the same thing – form gluten? Well, yes, ultimately; but when you knead dough, you also oxidize it (expose it to oxygen). Over-oxidized (or, over-kneaded) dough results in color and flavor loss in a finished bread, which means it’s pale and tasteless. By giving the mixed flour and water time to go through autolysis on their own, you achieve the same result, but without any of the unpleasant effects of oxidation. Additionally, an autolyse period gives the flour time to soak up all the moisture, resulting in more orderly gluten formation (um, long story short).
What this all means for your bread is that your dough will be easier to handle before it’s baked, and the end product will taste better, have better texture, look better, and have better keeping qualities. What’s not to love?
Thanks to http://www.abreadaday.com/the-autolyse-method/ for this explanation.