Yogurt (or sometimes written as "yoghurt") is a product that is made by a fermentation of lactose to form lactic acid. The fermentation process occurs due to the presence of live and active cultures. As the fermentation progresses, milk protein coagulates as the pH in the mixture decreases. The texture and flavor of finished product varies with the combination of different live cultures that was used in the process.

It is traditionally made with dairy milk, such as the one from cow, buffalo, goat or sheep, but in recent years, non-dairy yogurt, such as a yogurt made with soy milk, is available in a market.