Place the starter culture or active-culture yogurt in a large bowl. Add the dry milk powder, if using. If you want a thicker yogurt, add 1 teaspoon unflavored gelatin, mixed with a small amount of milk.
Warm milk to 110°F (use a thermometer) in a 1- to 2-quart saucepan or double boiler.
Add a small amount of the warmed milk to the active-culture yogurt or starter culture and stir.
Slowly add the rest of the warmed milk to the mixture. Stir well.
Cover the bowl and place the mixture into a commercial yogurt maker, an oven on very low heat (200°F), a heating pad, or a warm spot in your kitchen. Leave until set, about 6-8 hours. Use the thermometer to make sure the temperature stays at 100°F.
When set, refrigerate the yogurt for 8 hours before eating.
After the yogurt is set, you can stir in fruit and/or flavorings. To sweeten, try 2-4 teaspoons honey or sugar.
To make drinkable yogurt, add additional milk and/or fruit syrups to taste, after the yogurt is done.
To make frozen yogurt, follow the directions on your ice cream maker, using the homemade yogurt instead of cream or milk.
To make yogurt cheese (which can be used as a substitute for cream cheese or in cooking), drain yogurt in a strainer lined with cheesecloth and leave overnight (cover the entire bowl, yogurt and strainer with a cloth).
In the morning, drain the liquid in the bowl. Place a weight (you can use a sealed plastic bag filled with water) on the cheese, cover again, and let stand another 8 hours. Wrap yogurt cheese and refrigerate.You can purchase dried starter cultures, or just get some plain yogurt containing live culture. Make sure the carton says it contains "live culture" or "active yogurt culture". Many pasteurized yogurts no longer contain the active ingredient.*Low-fat is healthiest, but the higher the fat content, the creamier and smoother the yogurt will be.Nutritional value of this recipe is based on the use of low-fat milk.