In a glass measuring cup or microwavable bowl, heat water in the microwave for 20 seconds; this should result in a temperature of 80-90F.
If you're using Fresh or Active Dry Yeast, mix the yeast into the water and let sit for 2 minutes. If you're using Instant Dry Yeast (IDY), proceed to the next step. Note: Caputo yeast is labeled as Active yeast, but does not need to be activated in water (works as IDY).
Add the flour (preferment section only!) and IDY yeast to the bowl of a stand mixer. Next, add the water (preferment section only!) and mix well with hands, or a spoon, until fully incorporated.
Cover with a lid or saran wrap, tightly. Allow to sit at room temperature for 2 hours before placing in the refrigerator for 18-24 hours.