The main substance in yogurt is milk, which serves as the primary ingredient in its production. Yogurt is created through the process of fermentation, where specific strains of bacteria, primarily Lactobacillus bulgaricus and Streptococcus thermophilus, convert lactose (the sugar found in milk) into lactic acid. This fermentation process thickens the milk and gives yogurt its distinctive tart flavor and creamy texture. Yogurt is not only a popular health food, packed with probiotics and beneficial nutrients, but also versatile in culinary uses, appearing in snacks, smoothies, and as an ingredient in numerous dishes worldwide.