I use whole milk for 2 reasons. The first is that to get the fat out of whole milk they use a chemical to make the fat rise to the surface. Unfortunately, the chemical does not dissipate from the milk after the process and who knows what the long term effects of it may have. ( I much prefer natural with no chemicals, preservatives or colors!) Secondly, yogurt made with whole milk is much creamers and also takes less time to make. I always hold back a cup of yogurt each week to make the next batch. If this is your first time, you can buy a container of plain yogurt from the store to get you started. My first time I used a small container of Greek yogurt and it worked very well. Now I just save some of my current batch for the next batch. Un-pasteurized Method: In a large pot, heat 1 gallon of whole milk until it starts to boil and bubble up the sides. You can use a candy thermometer if you wish (If your new to making yogurt, I recommend buying one. You can usually pick one up for under $5). If you are using a thermometer, it should boil until it is 180°. Heat your milk to 180°. Be care not to over heat. Turn off stove and remove pot. Let cool until it is approx. 110°. If you don't have a thermometer, test it like you would a baby bottle, on your wrist to make sure it isn't too hot. In a small bowl, put your starter yogurt in and add a cup or two of the cooled milk. Whisk until dissolve and / or smooth. Add rest of milk and whisk until fully mixed. Pour into your desired containers. Do NOT put a lid on yet. If your not using a yogurt maker, put a piece of plastic wrap over the top and carefully wrap in a heavy warm towel. Put in a warm place that is between 110° to 115° for several hours until thick. When set, put into containers and refrigerate immediately. Should be ready to eat the next day. You can add whatever you like to it. I have tried everything from a little bit of vanilla to a tablespoon of cherry preserves. Pasteurized Method: If your using pasteurized milk, you can simply let the milk and the starter yogurt both get to room temperature add them together, mixing until smooth. Pour into containers and wrap and keep warm as in the above method.