A yogurt starter is a blend of bacteria that consume lactose in milk and convert it to lactic acid, which gives yogurt its tangy flavor and thick texture. The starter is added to milk to begin the fermentation process that turns it into yogurt. Yogurt starters can be purchased in stores or online, or they can be made at home by using a small amount of store-bought yogurt as a starter. There are many varieties of yogurt starter cultures to choose from, including Greek, Bulgarian, vegan, and kosher. Some starters require long-term maintenance, while others can be used as needed without the need for long-term culture maintenance. The type of starter used can affect the flavor, consistency, and perpetuation and culturing temperature of the resulting yogurt.