How can I make yogurt without using yogurt as an ingredient?

To make yogurt without using yogurt as an ingredient, you can use a starter culture containing live bacteria cultures, such as Lactobacillus bulgaricus and Streptococcus thermophilus. These cultures can be purchased in powdered form or from a previous batch of homemade yogurt. Heat milk to a specific temperature, add the starter culture, and allow it to ferment at a warm temperature for several hours until it thickens into yogurt.