Yogurt, also spelled yoghurt or yoghourt, is a favorite breakfast, lunch, or snack food found in the dairy aisle of the grocery store. A thick, custard- or pudding-like food, yogurt is made by the natural bacterial fermentation of milk.

The process of making yogurt involves culturing cream or milk with live and active bacterial cultures; this is accomplished by adding bacteria directly to the milk. Commercially made yogurt is usually made with a culture of Lactobacillus acidophilus and Streptococcus thermophilis. Some manufacturers use Lactobacillus bulgaricus rather than L. acidophilus. Yogurt made at home is usually started by adding a dab of commercially made yogurt to boiled milk, and then keeping the mixture at 112° Fahrenheit (45° Celsius).

In Western cultures, yogurt is enjoyed in a variety of ways, most popularly as a cool dish mixed with fruit. Yogurt can be used to make healthy shakes or frozen to eat like ice cream. Yogurt can also be used when cooking, in place of milk, sour cream, and even some cheeses. In Middle Eastern cultures, yogurt is frequently served with meat, meat sauces, and vegetables. It can be mixed with various other sauces or used as a tangy dollop on top of a meal.

When purchasing store-bought yogurt, consumers should always check the label for live cultures. If yogurt has been pasteurized or heated after the cultures have been added, more than likely, the cultures will die. Properly made yogurt will keep well in a refrigerator at 40° Fahrenheit (4° Celsius) for up to ten days. After this amount of time, the cultures often become weak.

Historically, some of the first yogurt most likely consisted of goat’s milk that fermented in the goatskin bags carried by early nomadic people of Turkish origin. Today, yogurt is primarily made with cow’s milk in the United States, but around the world, it is also made with the milk of goats, sheep, buffalo, and even camels.

It is easy and inexpensive to make yogurt at home. Simply boil milk, lower its temperature to 112°F (45°C) and then add a spoonful of store-bought yogurt to a small amount of the milk. Stir it well, and then add the rest of the warm milk. Keep the whole batch in a warm place for several hours so the yogurt can set. When the yogurt is ready, refrigerate immediately. To enjoy, add fresh fruit, jam, granola, honey, or anything else that strikes your fancy.