These two components make up a cultured dairy product and can be seen when a batch of kefir is cultured for a bit longer than usual or when you allow raw milk to clabber until a separation is reached.
I like using whey as a general culture starter in things like lacto-fermented lemonade or juices, or for the creamy cheese the process produces. I have also, in the very early days of fermenting vegetables, used it as a starter for fermenting sauerkraut, salsa, and pickles. I forgo the whey now when fermenting vegetables, but still like to make whey from time to time.
Line a strainer with a coffee filter, clean tea towel, or layers of cheesecloth. Place over a deep bowl.
Allow the clear whey to drip out the bottom. If it is milky looking, then you’ll want to survey your straining system for leaks and start over. You want the whey to be clear and free from milk solids.
A few hours of straining will produce a soft, easily spreadable cheese or Greek-style yogurt texture. An overnight dripping session will yield more whey and result in a dense, cream cheese-like texture.
Store whey in a jar in the refrigerator, which should keep for months if properly strained. The cheese can be eaten within a week or two.
But I dare you not to eat it off the spoon right then and there.