I'm new to the group so please forgive if this has been covered, but a search in this thread pulled up nothing on yogurt making. It’s fun to do off grid, far better for you than store bought and costs well under half what storebought does, either regular or Greek. And no junk ingredients!!
Here’s what you need. A room temperature ice chest, one or more mason or other jars of the same size (quart or pint) and an instant read thermometer. The setup will be hot water poured into your ice chest (125 degrees is ideal), filling it only as high as needed to not seep into your jar(s) once they're added. That's your incubator. Once the yogurt jars are entered into the warm bath in the ice chest, you close the lid and forget it for 8-9 hours. Note that you do want to locate the chest in a warm place where it won’t be disturbed at all, so outside off path is ideal, either in partial shade if it’s hot or if not, you can blanket-wrap the ice chest to keep it snuggled in. As the 8-9 hours goes by, the water temp will reduce but that's fine. Just keep it blanketed or warm otherwise. Once done, don't toss the bath water, you can use it for dishwashing, cleaning or whatever. So that's the setup and how to incubate the yogurt. Very simple! Hot water in an ice chest. Pffft.
Procedure for MAKING the yogurt: Simpler than dirt. Heat milk to 180 degrees. That’s just shy of scalding where it climbs up the pot. Then cool it back down to 115-118 degrees. Add 1 Tbsp. plain yogurt from store (your beginning culture or "starter") PER 1 Cup of milk used. Mix thoroughly but gently. Cap jars (plastic caps are fine) and place into your warm water bath within ice chest, making sure the bath water stays below entry level. Re-wrap ice chest with blanket if using one. Then just leave it alone 8-9 hours. No moving, no bumping, nothing. (Proteins are mating.) After the 8-9 hours, refrigerate yogurt jars overnight. If you want Greek (thickened), there’s another step. You just plop the yogurt into a fine mesh strainer (cheesecloth is traditional but messy whereas reuseable mesh basket coffee filters work GREAT and most supermarkets have them). About an hour in strainer (can do in fridge) will drain the whey out, leaving a thicker yogurt.
Now! If you want to watch your dog trance out from decadent, slurpy-sleepy pleasure, give the whey to dog. Lots of protein! (I personally think it takes them back to newborn days.) I actually use it for bread baking in place of water.
Once fully cold, spoon a serving into a bowl and whip it a bit with your spoon, then flavor it. You can use jam or maple syrup, done deal – or what I use is a very thin wedge of lemon or lime, squeezed to its death to get every drop PLUS honey and sometimes also PLUS a few drops vanilla extract. Honey has very good health benefits and the yogurt itself is super good for women due to the calcium, protein and our unique “fauna and flora.” It keeps about a week in fridge. I don't like plain yogurt, but with flavoring (sky's limit) -- actually I've gotten totally addicted to it. But admit, it's just always really really fun to make it.